SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 6-K

Report of Foreign Private Issuer
Pursuant to Rule 13a-16 or 15d-16 of the

Securities Exchange Act of 1934

For the month of November, 2025

Commission File Number 1-14732

COMPANHIA SIDERÚRGICA NACIONAL

(Exact name of registrant as specified in its charter)

National Steel Company

(Translation of Registrant's name into English)

Av. Brigadeiro Faria Lima 3400, 20º andar
São Paulo, SP, Brazil
04538-132

(Address of principal executive office)

Indicate by check mark whether the registrant files or will file annual reports
under cover Form 20-F or Form 40-F. Form 20-F ___X___ Form 40-F _______

Indicate by check mark whether the registrant by furnishing the information contained in this Form is also thereby furnishing the information to the Commission pursuant to Rule 12g3-2(b) under the Securities Exchange Act of 1934.

Yes _______ No ___X____

Companhia Siderúrgica Nacional S.A.
BALANCE SHEET
(In thousands of Reais)


		Consolidated		Parent Company				Consolidated		Parent Company
	Notes	09/30/2025	12/31/2024	09/30/2025	12/31/2024		Notes	09/30/2025	12/31/2024	09/30/2025	12/31/2024
ASSET						LIABILITIES AND SHAREHOLDERS' EQUITY
Current						Current
Cash and cash equivalents	3	16,526,099	23,310,197	700,793	5,666,618	Borrowings and financing	12	8,852,012	8,821,679	4,926,573	5,201,174
Financial investments	4	914,077	911,378	896,613	895,573	Payroll and related taxes		688,931	560,695	232,445	184,696
Trade receivables	5	2,706,484	2,900,998	1,442,171	1,555,141	Trade payables	15	7,087,400	7,030,734	3,638,920	3,596,080
Inventory	6	10,265,297	10,439,741	6,506,401	6,839,246	Tax payables		761,584	719,253	132,874	195,063
Recoverable taxes	7	1,300,556	1,367,316	404,514	668,137	Labor and civil provisions	18	106,628	132,112	73,525	61,008
Other current assets	8	1,124,136	856,063	1,182,681	1,012,495	Advances from customers	16	4,097,692	3,648,639	415,969	382,350
Total current assets		32,836,649	39,785,693	11,133,173	16,637,210	Dividends and interest on equity payable	16	4,425	61,965	6,094	6,242
						Trade payables – forfaiting	15.a	2,182,867	2,902,593	1,416,596	2,214,482
Non-Current						Other payables	16	1,039,675	1,238,805	965,567	1,174,978
Long-term realizable asset						Total current liabilities		24,821,214	25,116,475	11,808,563	13,016,073
Financial investments	4	24,864	169,977		142,423
Deferred taxes assets	17.b	6,646,949	7,345,326	4,475,408	4,750,333	Non-Current
Inventory	6	2,030,856	1,761,172			Borrowings and financing	12	43,294,938	48,092,942	22,462,624	25,044,466
Recoverable taxes	7	3,653,742	2,799,951	2,485,087	1,838,343	Deferred taxes assets	17.b	632,529	541,329
Other non-current assets	8	4,865,058	5,232,370	5,711,140	5,360,281	Provision for tax, social security, labor, civil and environmental risks	18	798,575	1,245,590	284,077	276,689
		17,221,469	17,308,796	12,671,635	12,091,380	Employee benefits		516,536	473,046	495,333	454,161
						Provisions for environmental liabilities and decommissioning	19	1,203,930	1,133,363	133,842	142,989
Investments	9	7,163,009	5,948,051	27,835,808	26,292,822	Provision for investment losses	9			10,723,415	11,458,813
Property, plant and equipment	10	32,610,732	30,426,023	10,352,409	9,664,413	Other payables	16	12,202,503	11,844,793	2,007,904	2,089,266
Intangible assets	11	10,993,733	10,438,091	64,657	68,070	Total non-current liabilities		58,649,011	63,331,063	36,107,195	39,466,384
Total non-current assets		67,988,943	64,120,961	50,924,509	48,116,685
						Shareholders’ equity
						Paid-up capital	21	10,240,000	10,240,000	10,240,000	10,240,000
						Capital reserves	21.a	2,056,970	2,056,970	2,056,970	2,056,970
						Legal reserves		1,158,925	1,158,925	1,158,925	1,158,925
						Earnings reserves		640,460	3,232,313	640,460	3,232,311
						Net income/(loss)		(922,226)	(2,591,853)	(922,226)	(2,591,851)
						Other comprehensive income		967,795	(1,824,917)	967,795	(1,824,917)
						Total shareholders' equity of controlling shareholders		14,141,924	12,271,438	14,141,924	12,271,438
						Earnings attributable to the non-controlling interests		3,213,443	3,187,678
						Total shareholders' equity		17,355,367	15,459,116	14,141,924	12,271,438
TOTAL ASSETS		100,825,592	103,906,654	62,057,682	64,753,895	TOTAL LIABILITIES AND SHAREHOLDERS' EQUITY		100,825,592	103,906,654	62,057,682	64,753,895
The Accompanying notes are an integral part of these consolidation financial statement

Companhia Siderúrgica Nacional S.A.
Statements of Income
(In thousands of Reais)

			Consolidated		Controladora		Consolidated		Controladora
		Nine-month period ended		Nine-month period ended		Three-month period ended		Three-month period ended
	Notes	9/30/2025	9/30/2024	9/30/2025	9/30/2024	9/30/2025	9/30/2024	9/30/2025	9/30/2024

Net Revenue	23	33,394,783	31,661,321	12,553,574	13,945,349	11,793,868	11,066,589	3,887,573	5,073,830
Costs of goods sold and services rendered	24	(24,669,191)	(23,747,585)	(11,764,717)	(13,313,207)	(8,326,618)	(8,332,916)	(3,715,938)	(4,758,178)
Gross profit		8,725,592	7,913,736	788,857	632,142	3,467,250	2,733,673	171,635	315,652

Operating (expenses)/income		(4,471,770)	(4,935,811)	(312,678)	(1,333,437)	(1,743,821)	(1,952,192)	(31,978)	(310,106)
Selling expenses	24	(3,621,674)	(4,054,126)	(593,846)	(624,542)	(1,328,433)	(1,492,210)	(178,965)	(210,872)
General and administrative expenses	24	(712,210)	(647,360)	(286,623)	(282,179)	(231,287)	(216,443)	(90,719)	(91,003)
Equity in results of affiliated companies	9	401,854	314,304	1,177,153	106,158	156,627	122,705	435,178	182,972
Other operating (expenses)/income, net	25	(539,740)	(548,629)	(609,362)	(532,874)	(340,728)	(366,244)	(197,472)	(191,203)
Other operating income		192,574	683,639	113,947	135,453	48,765	105,569	(28,363)	32,646
Other operating expenses		(732,314)	(1,232,268)	(723,309)	(668,327)	(389,493)	(471,813)	(169,109)	(223,849)

Income before financial income (expenses)		4,253,822	2,977,925	476,179	(701,295)	1,723,429	781,481	139,657	5,546
Financial income (expenses), net	26	(5,193,419)	(4,551,506)	(2,371,817)	(2,126,000)	(1,442,833)	(1,931,588)	(539,990)	(1,167,198)
Financial income		1,233,371	992,638	639,146	431,365	407,396	273,672	208,699	96,378
Financial expenses		(4,947,507)	(4,985,542)	(2,231,167)	(2,516,463)	(1,473,826)	(1,820,640)	(617,726)	(953,047)
Other financial items, net		(1,479,283)	(558,602)	(779,796)	(40,902)	(376,403)	(384,620)	(130,963)	(310,529)

Income before income taxes	17	(939,597)	(1,573,581)	(1,895,638)	(2,827,295)	280,596	(1,150,107)	(400,333)	(1,161,652)
Income tax and social contribution		154,086	120,437	973,412	868,478	(204,158)	399,237	263,253	321,315

Net income for the period		(785,511)	(1,453,144)	(922,226)	(1,958,817)	76,438	(750,870)	(137,080)	(840,337)

Attributable to:
Earnings attributable to the controlling interests		(922,226)	(1,958,817)	(922,226)	(1,958,817)	(137,080)	(840,337)	(137,080)	(840,337)
Earnings attributable to the non-controlling interests		136,715	505,673			213,518	89,467

Loss basic and diluted per share (in R$)	21.e			(0.69545)	(1.47713)			(0.10337)	(0.63369)
The Accompanying notes are an integral part of these consolidation financial statement

				Consolidated
	Nine-month period ended		Three-month period ended
	09/30/2025	09/30/2024	09/30/2025	09/30/2024
Net income/(loss)	(785,511)	(1,453,144)	76,438	(750,870)

Other comprehensive income
Items that will not be subsequently reclassified to the statement of income
Actuarial gains/(losses) over pension plan of subsidiaries, net of taxes	1,066	(1,295)	993	40
	1,066	(1,295)	993	40

Items that could be subsequently reclassified to the statement of income
Cumulative translation adjustments for the year	(90,236)	452,670	(87,153)	73,466
(Loss)/gain cash flow hedge accounting, net of taxes	2,262,203	(1,476,000)	343,804	312,401
Cash flow hedge reclassified to income upon realization, net of taxes	147,115	(7,987)	5,195	772
(Loss)/gain cash flow hedge accounting – “Platts” from investments in subsidiaries, net of taxes	673,254	77,083	163,687	76,848
	2,992,336	(954,234)	425,533	463,487

	2,993,402	(955,529)	426,526	463,527

Comprehensive income for the year	2,207,891	(2,408,673)	502,964	(287,343)

Attributable to:
Earnings attributable to the controlling interests	1,862,539	(2,929,954)	238,719	(392,369)
Earnings attributable to the non-controlling interests	345,352	521,281	264,245	105,026
	2,207,891	(2,408,673)	502,964	(287,343)

				Parent Company
	Nine-month period ended		Three-month period ended
	09/30/2025	09/30/2024	09/30/2025	09/30/2024
Net income/(loss)	(922,226)	(1,958,817)	(137,080)	(840,337)

Other comprehensive income

Items that will not be subsequently reclassified to the statement of income
Actuarial gains/(losses) over pension plan of subsidiaries, net of taxes	1,065	(1,297)	991	40
	1,065	(1,297)	991	40

Items that could be subsequently reclassified to the statement of income
Cumulative translation adjustments for the year	(90,236)	452,670	(87,153)	73,465
(Loss)/gain cash flow hedge accounting, net of taxes	2,262,203	(1,476,000)	343,804	312,401
Cash flow hedge reclassified to income upon realization, net of taxes	147,115	(7,987)	5,195	771.41
(Loss)/gain cash flow hedge accounting – “Platts” from investments in subsidiaries, net of taxes	464,618	61,477	112,962	61,290

	2,783,700	(969,841)	374,808	447,928

	2,784,765	(971,137)	375,799	447,968

Comprehensive income for the year	1,862,539	(2,929,954)	238,719	(392,369)
The Accompanying notes are an integral part of these consolidation financial statement

Companhia Siderúrgica Nacional S.A.
Statements of Changes in Equity
(In thousands of Reais)
			de capital
				Capital	Legal
	Paid-up capital	Treasury shares	Capital transactions	Reserves			Retained earnings	Other comprehensive income	Total Shareholders' Equity Parent Company	Non-controlling interest	Total Consolidated Shareholders' Equity
	Paid-up capital	Treasury shares	Capital transactions	Capital	Legal	Statutory	Retained earnings	Other comprehensive income	Total Shareholders' Equity Parent Company	Non-controlling interest	Total Consolidated Shareholders' Equity
Balances on December 31, 2024	10,240,000	(223,830)	2,248,080	32,720	1,158,925	640,460		(1,824,917)	12,271,438	3,187,678	15,459,116

Adjusted opening balances	10,240,000	(223,830)	2,248,080	32,720	1,158,925	640,460		(1,824,917)	12,271,438	3,187,678	15,459,116

Total comprehensive income							(922,226)	2,792,712	1,870,486	(57,508)	1,812,978

Net loss							(922,226)		(922,226)	136,715	(785,511)
-
Other comprehensive income								2,792,712	2,792,712	(194,223)	2,598,489
Actuarial gains/(losses) over pension plan of subsidiaries, net of taxes								1,065	1,065	1	1,066
Cumulative translation adjustments for the year								(90,236)	(90,236)		(90,236)
(Loss)/gain cash flow hedge accounting, net of taxes								2,262,203	2,262,203		2,262,203
Cash flow hedge reclassified to income upon realization, net of taxes								147,115	147,115		147,115
(Loss)/gain cash flow hedge accounting – “Platts” from investments in subsidiaries, net of taxes								464,618	464,618	208,636	673,254
Gain on the percentage change in investments								7,947	7,947		7,947
Allocation of profit/(loss) for the year										(402,860)	(402,860)
Dividends approved at SBM 05/08/2025										(337,783)	(337,783)
Interest on shareholders' equity approved at SBM 05/08/2025										(65,077)	(65,077)
Capital transactions										83,273	83,273
Constitution of subsidiaries in foreign operations										1,170	1,170
Result of acquisition of ownership interest in Grupo Estrela										82,103	82,103
Balances as at September 30 2025	10,240,000	(223,830)	2,248,080	32,720	1,158,925	640,460	(922,226)	967,795	14,141,924	3,213,443	17,355,367

Companhia Siderúrgica Nacional S.A.
Statements of Cash Flows
(In thousands of Reais)

			Consolidated		Parent Company
	Notes	09/30/2025	09/30/2024	09/30/2025	09/30/2024

Net cash from operating activities		(1,006,669)	5,102,490	(1,331,862)	(925,155)
Cash flow from operating activities		3,369,715	4,782,847	474,387	(175,473)
Earnings attributable to the controlling interests		(922,228)	(1,958,720)	(922,228)	(1,958,818)
Earnings attributable to the non-controlling interests		136,715	505,673
Adjustments to reconcile the result:
Financial charges in borrowing and financing raised	26	2,933,782	2,924,941	1,376,689	1,307,125
Financial charges in borrowing and financing granted		(302,167)	(119,777)	(269,558)	(165,671)
Charges on lease liabilities	14	84,137	73,876	2,586	1,233
Equity in results of affiliated companies	9	(401,854)	(314,304)	(1,177,153)	(99,504)
Deferred taxes assets	17.b	(794,545)	(1,016,726)	(966,240)	(868,478)
Provision for tax, social security, labor, civil and environmental risks		(469,389)	32,628	19,905	43,359
Exchange, Monetary and Cash Flow Hedge		(260,222)	1,326,769	1,182,577	80,674
Write-off of property, plant and equipment right of use and Intangible assets	9, 10, 11 and 14	36,454	32,334	(11,427)	20,443
Provision for environmental liabilities and decommissioning of assets		70,553	58,556	(9,147)	(10,381)
Updated shares – Fair value through profit or loss	26	166,167	508,311	166,167	542,108
Depreciation, amortization and depletion	24	3,088,296	2,797,924	1,074,077	983,338
Accrued/(reversal) for consumption and services		(56,814)	(88,991)	6,376	(28,600)
Dividends USIMINAS		(4,907)	(45,063)	(4,835)	(44,912)
Other provisions		65,737	65,416	6,598	22,611

Changes in assets and liabilities		(4,376,384)	319,644	(1,806,249)	(749,682)
Trade receivables - third parties		510,591	586,625	298,545	(168,781)
Trade receivables - related party		4,512	(2,911)	(211,892)	716,897
Inventory		(415,253)	(1,204,709)	(63,588)	(937,038)
Dividends and receivables - related parties		27,618	45,063	938,113	1,153,746
Recoverable taxes		(766,239)	35,082	(383,121)	(16,581)
Judicial deposits		27,211	(150,354)	(23,588)	7,866
Receipt of RFFSA receivables		(506,381)	442,246	(506,381)	442,246
Other assets		(122,751)	313,754	(102,038)	(29,837)
Trade payables		(204,001)	(644,274)	6,999	18,237
Trade payables – Forfaiting and Drawee risk		(715,335)	(482,380)	(797,886)	(1,022,709)
Payroll and related taxes		98,254	165,977	47,750	68,918
Tax payables		(9,134)	(516,748)	(60,813)	21,062
Payables to related parties		7,623	(22,066)	48,196	54,248
Advance of customers of mineral and energy contracts		297,957	4,445,402	(270,359)	93,685
Interest paid	12.a	(3,056,397)	(2,794,212)	(1,326,124)	(1,158,345)
Interest received				1,035	1,391
Receipts/(Payments) from hedging operations, cash flow and derivatives		(230,184)	(49,618)	(65,236)	(16,757)
Other liabilities		169,144	152,766	157,758	22,071

Net cash investment activities		(4,615,465)	(3,435,874)	(2,990,948)	(1,932,904)
Investments / AFAC / Acquisitions of Shares		(23,600)	(32,000)	(110,858)	(143,953)
Cash received in acquisition of Gramperfil		13,261
Purchase of property, plant and equipment, intangible assets and investment property	9, 10 and 11	(3,893,115)	(3,435,772)	(1,580,574)	(1,643,683)
Intercompany loans granted		(57,911)	(71,531)	(591,050)	(138,603)
Intercompany loans received		6,124	8,768	3,888	3,888
Financial Investments, net of redemption		(454,385)	94,661	(455,417)	(10,553)
Acquisition of Gramperfil's investments		(35,948)
Acquisition of Grupo Estrela's investments		(300,000)		(300,000)
Sale of financial assets		43,063		43,063
Cash received in acquisition of Grupo Estrela		87,046
Net cash used in financing activities		(1,179,339)	848,131	(643,015)	2,060,660
Borrowings and financing raised	12.a	10,072,906	7,903,465	2,342,882	3,585,289
Transactions cost - Borrowings and financing		(113,275)	(89,929)	(11,240)	(47,584)
Borrowings and financing – related parties	12.a				2,487,558
Amortization of borrowings and financing	12.a	(10,427,053)	(5,181,446)	(2,373,222)	(2,166,531)
Amortization of borrowings and financing - related parties	12.a			(591,569)	(839,238)
Amortization of leases	14	(269,986)	(223,959)	(9,866)	(9,445)
Advance iron ore payments		66,717
Amortization advance iron ore payments		(66,717)
Repurchase of Treasury Shares			(327,069)
Dividends and interest on shareholder’s equity		(441,931)	(1,232,931)		(949,389)

Exchange Variation on Cash and Equivalents		17,375	(108,557)

Increase (decrease) in cash and cash equivalents		(6,784,098)	2,406,190	(4,965,825)	(797,398)
Cash and equivalents at the beginning of the year		23,310,197	16,046,218	5,666,618	2,270,070
Cash and equivalents at the end of the year		16,526,099	18,452,408	700,793	1,472,672
The Accompanying notes are an integral part of these consolidation financial statement

Companhia Siderúrgica Nacional S.A.
Statements of Value Added
(In thousands of Reais)

		Consolidated		Parent Company
	09/30/2025	09/30/2024	09/30/2025	09/30/2024
Revenues
Sales of products and services rendered	37,939,753	35,992,315	15,381,371	16,815,727
Other income/(expenses)	138,669	114,608	122,817	64,624
Provision for (reversal of) doubtful debts	(8,955)	(28,757)	(1,269)	(20,042)
	38,069,467	36,078,166	15,502,919	16,860,309
Raw materials acquired from third parties
Cost of sales and services	(17,399,022)	(17,094,775)	(9,420,988)	(10,953,809)
Materials, electric power, outsourcing and other	(4,232,059)	(4,348,444)	(941,805)	(985,134)
Impairment/recovery of assets	(120,519)	(45,184)	(65,720)	(91,642)
	(21,751,600)	(21,488,403)	(10,428,513)	(12,030,585)
Gross value added	16,317,867	14,589,763	5,074,406	4,829,724

Retentions
Depreciation, amortization and depletion	(3,088,297)	(2,793,742)	(1,074,078)	(982,697)
Value added created	13,229,570	11,796,021	4,000,328	3,847,027

Value added received
Equity in results of affiliated companies	401,854	314,304	1,177,153	106,158
Financial income	1,233,371	484,327	639,146	(76,946)
Other and exchange gains	1,294,075	678,567	59,623	(1,589)
	2,929,300	1,477,198	1,875,922	27,623
Value added for distribution	16,158,870	13,273,219	5,876,250	3,874,650

Value added distributed
Personnel and Charges	3,411,766	3,134,308	1,260,389	1,212,092
Salaries and wages	2,690,272	2,496,916	942,236	924,172
Benefits	557,321	498,535	255,428	235,635
Severance payment (FGTS)	164,173	138,857	62,725	52,285
Taxes, fees and contributions	5,804,211	5,859,443	2,463,484	2,568,236
Federal	3,120,564	3,088,265	1,196,147	1,315,100
State	2,662,437	2,756,526	1,267,337	1,253,136
Municipal	21,210	14,652
Remuneration on third-party capital	7,728,404	5,732,612	3,074,603	2,053,139
Interest	4,607,421	3,564,447	2,293,589	1,619,425
Rental	7,538	18,212	4,017	5,674
Other and exchange losses	3,113,445	2,149,953	776,997	428,040
Interest on equity	(785,511)	(1,453,144)	(922,226)	(1,958,817)
Income for the year/Retained earnings	(922,226)	(1,958,817)	(922,226)	(1,958,817)
Non-controlling interests	136,715	505,673
	16,158,870	13,273,219	5,876,250	3,874,650
The Accompanying notes are an integral part of these consolidation financial statement

EXPLANATORY NOTES TO THE INTERIM INFORMATION

(In thousands of reals, unless stated otherwise)

OPERATING CONTEXT

Companhia Siderúrgica Nacional (CSN) is a publicly-held corporation headquartered in the capital of the state of São Paulo. Founded on April 9, 1941 during the mandate of former Brazilian president Getúlio Vargas, the Company was privatized in 1993. CSN (referred to as “the Company" or “the Parent Company"), together with its subsidiaries, controlled entities, jointly controlled entities and affiliates (referred to as “the Group"), operates across five main business segments:

(i)

Steel industry: production and marketing of flat and long steels;

(ii)

Mining: mining and processing of iron ore, tin, limestone and dolomite, as well as the sale of iron ore;

(iii)

Cements: production and marketing of bagged and bulk cement, as well as aggregates and other related products;

(iv)

Energy: generation and sale of energy from almost all renewable sources and;

(v)

Logistics: ownership interest in railways, port concessions and vehicle fleets.

CSN is listed on São Paulo’s B3 S.A. – Brasil, Bolsa, Balcão stock exchange (B3) under the code CSNA3, where its shares are traded, as well as on the NYSE - United States stock exchange, under the code SID. Additionally, its subsidiaries CSN Mineração S.A. and Companhia Estadual de Geração de Energia Elétrica – CEEE-G, are publicly traded, and CSN Mineração S.A. trading common shares on B3 under the ticker CMIN3.

CSN Group maintains significantly diversified business, being one of Brazil’s largest steel producers. The company is also the second largest exporter of iron ore and a pioneer in the stacking of tailings piles to de-characterize dams. It also occupies the position of the second largest player in the cement sector in the country.

Going concern:

Management understands that the Company has adequate resources to continue its operations. Accordingly, the Company's financial statements for the interim ended on September 30, 2025 were prepared based on the going concern assumption.

BASIS OF PREPARATION AND DECLARATION OF CONFORMITY

2.a)

Declaration of conformity

The individual and consolidated interim financial information ("interim financial information") was prepared and presented in accordance with accounting policies adopted in Brazil issued by the Accounting Pronouncements Committee ("CPC"), approved by the Brazilian Securities and Exchange Commission ("CVM") and the Federal Accounting Council ("CFC") and in accordance with the International Financial Reporting Standards ("IFRS") issued by the International Accounting Standards Board ("IASB"), currently referred to as IFRS Accounting Standards, and presents all the relevant information at the financial statements, and only this information, which correspond to those used by the Company's management in its activities. The consolidated interim financial information is identified as "Consolidated" and the interim financial information of the Parent Company is identified as "Parent Company".

EXPLANATORY NOTES TO THE INTERIM INFORMATION

(In thousands of reals, unless stated otherwise)

2.b)

Basis of presentation

The individual and consolidated interim financial information was prepared on a historical cost basis and adjusted to reflect: (i) the fair value measurement of certain financial assets and liabilities (including derivative instruments), as well as pension plan assets; and (ii) impairment losses. When IFRS and CPCs allow the option between acquisition cost or another measurement criterion, the acquisition cost criterion was used.

The preparation of this financial information requires Management to use certain accounting estimates, judgments and assumptions that affect the application of accounting policies and the reported amounts of assets, liabilities, revenues and expenses as of the balance sheet date, which may differ from actual future results. The assumptions used are based on historical data and other factors considered relevant and are reviewed by the Company's Management.

Interim financial information has been prepared and is presented in accordance with CPC 21 (R1) - "Interim Financial Reporting" and IAS 34 - "Interim Financial Reporting" in accordance with the standards established by the CVM. This interim financial information does not include all requirements for annual or complete financial statements and therefore must be read together with the Company's annual financial statements for the year ended December 31, 2024.

In this context, this interim financial information was not repeated either due to redundancy or relevance in relation to information previously presented in the following explanatory notes to the annual financial statements:

Note 2.d - Material accounting policies

Note 2.f - Adoption of new requirements, standards, amendments and interpretations

Note 9.b - Additional information on direct and indirect subsidiaries

Note 9.c - Main occurrences at subsidiaries in 2024 and 2023

Note 11.a - Assets with indefinite useful lives

Note 12 – Impairment of assets

Note 19 - Taxes paid in installments

Note 22.a - Transactions with holding companies

Note 22.c - Other unconsolidated related parties

Note 30 - Employee benefits

Note 31 - Commitments

Note 32 - Insurance

The individual and consolidated financial information was approved by Management on November 4, 2025.

2.c)

Functional currency and presentation currency

The accounting records included in the financial information of each of the Company's subsidiaries are measured using the currency of the main economic environment in which each subsidiary operates ("functional currency"). The Parent Company and Consolidated interim information are presented in R$ (Reais), which is the Company's functional currency and the Group's presentation currency.

Transactions in foreign currencies are translated into the functional currency using the exchange rates prevailing on the dates of the transactions or valuation, in which the items are remeasured. The balances of the asset and liability accounts are translated at the exchange rate on the balance sheet date. As of September 30, 2025, US$ 1 is equivalent to R$ 5.3186 (R$ 6.1923 on December 31, 2024) and €1 is equivalent to R$ 6.2414 (R$ 6.4363 on December 31, 2024), according to rates extracted from the Central Bank of Brazil’s website.

EXPLANATORY NOTES TO THE INTERIM INFORMATION

(In thousands of reals, unless stated otherwise)

2.d)

Value added statement

According to Law 11.638/07, the presentation of the value added statement is required for all publicly-held companies. This statement was prepared in accordance with CPC 09 (R1) – Statement of Value Added. IFRS does not require the presentation of this statement; it is therefore presented as additional information.

2.e)

Adoption of new requirements, standards, amendments and interpretations

The new requirements, standards, amendments and interpretations that came into effect for fiscal years beginning on January 1, 2025, were:

Amendment to IAS 21 – The Effects of Changes in Foreign Exchange Rates;

OCPC 10 – Carbon credits (TCO2E), emissions allowances and decarbonization credits (CBIO);

Regarding the aforementioned changes, the Company did not identify significant impacts that would alter its disclosure concerning the adoption and interpretation of the standards.

International tax reform: On May 23, 2023, the International Accounting Standards Board issued the International Tax Reform – Pillar Two Model Rules – Amendments to IAS 12 (equivalent to CPC 32), which clarifies that IAS 12 (CPC 32) applies to income taxes arising from tax legislations enacted or substantially enacted to implement the Pillar Two model rules published by the OECD, including tax legislations that implement the total Qualified Domestic Top-Up Minimum Taxes of 15% as of 2025. The Company has been analyzing any impacts on its operations and based on amounts realized in the third quarter of 2025 and the projections for the end of the year, it has concluded that its Brazilian entities comply with the Transitional Safe Harbour Tests and their Globe effective rate meets the rules established in Law No. 15.079/24. As a result, there is no need for additional payments.

EXPLANATORY NOTES TO THE INTERIM INFORMATION

(In thousands of reals, unless stated otherwise)

CASH AND CASH EQUIVALENTS

		Consolidated		Parent Company
	09/30/2025	12/31/2024	09/30/2025	12/31/2024
Cash and banks
In Brazil	999,557	701,494	24,603	34,180
Abroad	10,893,439	13,318,603	48,289	868,839
	11,892,996	14,020,097	72,892	903,019

Financial investments
In Brazil	2,513,012	7,688,051	627,901	4,758,970
Abroad	2,120,091	1,602,049		4,629
	4,633,103	9,290,100	627,901	4,763,599
	16,526,099	23,310,197	700,793	5,666,618

The financial resources available in the country are basically invested in private and public securities with income linked to the variation of Interbank Deposit Certificates (CDI) and repurchase and resale agreements backed by fixed income securities. The Company applies part of the resources through exclusive investment funds, whose financial statements were consolidated in the Company.

The financial resources available abroad, held in dollars and euros, are invested in Time Deposit (TD) accounts remunerated at pre-fixed rates, as well as in accounts with automatic remuneration and daily liquidity. Yields are pegged to FED Funds and the ECB’s deposit rate. Investments are made in banks considered by Management as first-rate.

FINANCIAL INVESTMENTS

				Consolidated				Parent Company
	Current		Non-current		Current		Non-current
	09/30/2025	12/31/2024	09/30/2025	12/31/2024	09/30/2025	12/31/2024	09/30/2025	12/31/2024
Investments ⁽¹⁾	569,534	50,787	24,864	27,554	552,070	34,982
Usiminas shares ⁽²⁾	263,792	860,591			263,792	860,591
Bonds ⁽³⁾	80,751			142,423	80,751			142,423
	914,077	911,378	24,864	169,977	896,613	895,573		142,423

(1) These financial investments are restricted and linked to a Bank Deposit Certificate (CDB) used to secure a bank-issued letter of guarantee with financial institutions and Government bonds (LFT - Financial Treasury Bills) managed by the Company’s exclusive funds. The subsidiary CSN Cimentos Brasil maintains financial investments with restricted availability as collateral for a specific liability for which the redemption term is indefinite, with a balance of R$ 3,649 as of September 30, 2025 (R$ 8,497 on December 31, 2024). The subsidiaries Elizabeth Cimentos S/A and Estanho de Rondônia, on the other hand, hold investments linked to financing agreements that will mature in 2030 and 2028, respectively, in the amount of R$ 21,214 (R$ 19,057 on December 31, 2024). There are also R$ 543,793 in financial investments arising from the receipt of a registered warrant (RFFSA) that was blocked on September 30, 2025 due to bank clearance procedures. The amount was effectively cleared on October 3, 2025.

(2) The Company sold part of Usiminas' shares at market value according to the quotation provided on the transaction date, with a portion received immediately and the remainder in installments (See note 8). The investment’s final equity after the transaction was 4.99%.

(3) Bonds held with Banco Fibra maturing in February 2028 will be settled in advance by the end of the 2025 fiscal year. (See note 20.a.)

EXPLANATORY NOTES TO THE INTERIM INFORMATION

(In thousands of reals, unless stated otherwise)

TRADE RECEIVABLES

			Consolidated		Parent Company
	Ref.	09/30/2025	12/31/2024	09/30/2025	12/31/2024
Trade receivables
Third parties
In Brazil		1,401,661	1,457,840	606,391	868,360
Abroad		1,425,558	1,563,075	24,617	47,258
		2,827,219	3,020,915	631,008	915,618
(-) Estimated credit losses		(228,612)	(212,088)	(96,886)	(95,617)
		2,598,607	2,808,827	534,122	820,001
Related parties	20.a	107,877	92,171	908,049	735,140
		2,706,484	2,900,998	1,442,171	1,555,141

The composition of the gross balance of receivables from third party customers is shown as follows:

		Consolidated		Parent Company
	09/30/2025	12/31/2024	09/30/2025	12/31/2024
Current	2,420,909	2,522,661	470,577	821,965
Past-due up to 30 days	69,254	180,249	10,420	257
Past-due up to 180 days	78,798	139,106	17,076	1,442
Past-due over 180 days	258,258	178,899	132,935	91,954
	2,827,219	3,020,915	631,008	915,618

The changes in the expected credit losses for receivables from the Company's customers are as follows:

		Consolidated		Parent Company
	09/30/2025	12/31/2024	09/30/2025	12/31/2024
Opening balance	(212,088)	(226,053)	(95,617)	(119,558)
(Loss)/Reversal estimated	(13,722)	3,964	(4,937)	18,627
Recovery of receivables	4,767	10,001	3,668	5,314
Impact from acquisition of shareholding in Grupo Estrela ⁽¹⁾	(7,569)
Closing balance	(228,612)	(212,088)	(96,886)	(95,617)

(1) Transactions related to the acquisition of ownership interest in the Estrela Comércio e Participações S.A. group, which became effective on April 1, 2025. According to CPC 15 (R1) – Business combination, the Company has one year, as of this date, to form the respective business combination, which may impact the recorded fair value within this period based on an appraisal report.

The Company carries out credit assignment operations without co-obligation. After the assignment of the customer's trade bills/securities and receipt of the proceeds from the closing of each transaction, CSN settles the related receivables and fully discharges the credit risk of the transactions. Financial charges for the credit assignment operation during the period ended September 30, 2025 were R$ 56,402 in the consolidated statements and R$ 48,125 in the parent company, classified under financial income.

EXPLANATORY NOTES TO THE INTERIM INFORMATION

(In thousands of reals, unless stated otherwise)

INVENTORIES

		Consolidated		Parent Company
	09/30/2025	12/31/2024	09/30/2025	12/31/2024
Finished goods	3,767,026	4,250,175	2,299,992	2,623,991
Work in progress	4,350,124	3,976,448	1,961,642	1,888,560
Raw materials	2,577,899	2,845,578	1,567,701	1,902,306
Storeroom supplies	1,687,561	1,255,176	720,298	459,792
Advances to suppliers	35,358	23,463	10,400	1,432
Impact from acquisition of shareholding in Grupo Estrela ⁽¹⁾	15,906
(-) Provision for losses	(137,721)	(149,927)	(53,632)	(36,835)
	12,296,153	12,200,913	6,506,401	6,839,246

Classified:
Current	10,265,297	10,439,741	6,506,401	6,839,246
Non-current ⁽²⁾	2,030,856	1,761,172
	12,296,153	12,200,913	6,506,401	6,839,246

(2) Long-term inventories of iron ore that will be processed when implementing new beneficiation plants, which will generate Pellet Feed as a product. The start of operations is scheduled for the fourth quarter of 2027.

The changes in expected losses on inventories are as follows:

		Consolidated		Parent Company
	09/30/2025	12/31/2024	09/30/2025	12/31/2024
Opening balance	(149,927)	(121,871)	(36,835)	(24,304)
Reversal/(Provision for losses) on inventories with low turnover and obsolescence	12,206	(28,056)	(16,797)	(12,531)
Closing balance	(137,721)	(149,927)	(53,632)	(36,835)

RECOVERABLE TAXES

		Consolidated		Parent Company
	09/30/2025	12/31/2024	09/30/2025	12/31/2024
ICMS (Brazilian State Value-Added Tax)	2,102,854	1,717,546	1,362,364	1,116,394
Brazilian federal taxes ⁽¹⁾	2,696,064	2,336,854	1,505,471	1,376,319
Other taxes	155,380	112,867	21,766	13,767
	4,954,298	4,167,267	2,889,601	2,506,480

Classified:
Current	1,300,556	1,367,316	404,514	668,137
Non-current	3,653,742	2,799,951	2,485,087	1,838,343
	4,954,298	4,167,267	2,889,601	2,506,480

(1) The balance of Brazilian federal taxes mainly refers to PIS and COFINS, IRPJ and CSLL and IPI.

EXPLANATORY NOTES TO THE INTERIM INFORMATION

(In thousands of reals, unless stated otherwise)

The credits are mainly due to taxes levied on purchases of inputs and fixed assets as determined under current legislation. The realization of these credits generally occurs through offsetting with debts of the same nature

and/or other federal taxes, in the cases authorized by law. The Company's Management periodically evaluate recorded amounts and has not determined there to be greater risk regarding the realization of these tax credits.

OTHER ASSETS (CURRENT AND NON-CURRENT)

					Consolidated				Parent Company
		Current		Non-current		Current		Non-current
	Ref.	09/30/2025	12/31/2024	09/30/2025	12/31/2024	09/30/2025	12/31/2024	09/30/2025	12/31/2024
Judicial deposits	18			623,811	632,950			225,799	202,212
Derivative transactions	13	92,291	152,967
Dividends receivable	20.a	208,296	201,436			382,048	501,267
Prepaid expenses		369,672	327,403	16,629	9,770	182,166	208,557	15,436	6,093
Actuarial asset	20.a			51,973	47,708			40,533	37,059
Receivables from related parties	20.a	6,859	7,146	3,099,922	3,695,607	321,463	252,380	4,362,374	4,293,152
Loans with related parties		5,028	5,315	2,099,921	1,903,028	5,028	5,315	3,362,373	2,499,112
Other receivables from related parties		1,831	1,831	1,000,001	1,792,579	316,435	247,065	1,000,001	1,794,040
Other assets		447,018	167,111	1,072,723	846,335	297,004	50,291	1,066,998	821,765
Trading securities		3,236	2,947			3,051	2,814
Compulsory loans from Eletrobrás				73,969	51,012			71,003	48,437
Employee debts		111,345	92,628			51,996	47,332
Receivables by indemnity ⁽¹⁾				775,398	790,914			775,398	773,241
Receivables - Usiminas Shares ⁽²⁾		236,992		150,578	-	236,992		150,578
Term of Agreement GSF DFESA		5,943	14,264		2,377
Advances to suppliers		1,851	2,242
Others		87,651	55,030	72,778	2,032	4,965	145	70,019	87
		1,124,136	856,063	4,865,058	5,232,370	1,182,681	1,012,495	5,711,140	5,360,281

(1) The non-current assets of the consolidated and parent company are mainly composed of the net and certain credit arising from the final and unappealable decision in favor of the Company, mainly due to losses and damages resulting from voltage sinking in the energy supply in the periods from January/1991 to June/2002.

(2) The Company sold part of Usiminas' shares at market value according to the quotation provided on the transaction date, with a portion received immediately and the remainder in installments. The investment’s final equity after the transaction was 4.99%.

BASIS OF CONSOLIDATION AND INVESTMENTS

The accounting policies have been consistently applied to all consolidated companies. The consolidated financial information for the period ended September 30, 2025 and the consolidated financial statements for the year ended December 31, 2024 include the following direct and indirect subsidiaries and joint ventures, and associates as well as the exclusive funds, as follows:

EXPLANATORY NOTES TO THE INTERIM INFORMATION

(In thousands of reals, unless stated otherwise)

	Equity interests (%)
Companies	09/30/2025	12/31/2024	Core business
Direct interest in subsidiaries: full consolidation
CSN Islands VII Corp.	100,00	100,00	Financial transactions
CSN Inova Ventures	100,00	100,00	Equity interests and financial transactions
CSN Islands XII Corp.	100,00	100,00	Financial transactions
CSN Steel S.L.U.	100,00	100,00	Equity interests and financial transactions
TdBB S.A (*)	100,00	100,00	Equity interests
Sepetiba Tecon S.A.	99,99	99,99	Port services
Minérios Nacional S.A.	99,99	99,99	Mining and Equity interests
Companhia Florestal do Brasil	99,99	99,99	Reforestation
Estanho de Rondônia S.A.	99,99	99,99	Tin Mining
Companhia Metalúrgica Prada	99,89	99,89	Manufacture of containers and distribution of steel products
CSN Mineração S.A.	69,01	69,01	Mining
CSN Energia S.A.	99,99	99,99	Sale of electric power
FTL - Ferrovia Transnordestina Logística S.A.	92,71	92,71	Railroad logistics
Nordeste Logística S.A.	99,99	99,99	Port services
CSN Inova Ltd.	100,00	100,00	Advisory and implementation of new development project
CBSI - Companhia Brasileira de Serviços de Infraestrutura	99,99	99,99	Equity interests and product sales and iron ore
CSN Cimentos Brasil S.A.	99,99	99,99	Cement manufacturing
Berkeley Participações e Empreendimentos S.A.	100,00	100,00	Electric power generation and equity interests
CSN Inova Soluções S.A.	99,99	99,99	Equity interests
CSN Participações I	99,90	99,90	Equity interests
Circula Mais Serviços de Intermediação Comercial S.A.	0,10	0,10	Commercial intermediation for the purchase and sale of assets and materials in general
CSN Participações III	99,90	99,90	Equity interests
CSN Participações IV	99,90	99,90	Equity interests
CSN Participações V	99,90	99,90	Equity interests
CSN Incorporação e Participações Ltda.	99,99	99,99	Equity interests
Estrela Comércio e Participações S.A. ⁽⁵⁾	70,00		Equity interests

Indirect interest in subsidiaries: full consolidation
Lusosider Projectos Siderúrgicos S.A.	100,00	100,00	Equity interests and product sales
Lusosider Aços Planos, S. A.	100,00	100,00	Steel and Equity interests
CSN Resources S.A.	100,00	100,00	Financial transactions and Equity interests
Companhia Brasileira de Latas	99,89	99,89	Sale of cans and containers in general and Equity interests
Companhia de Embalagens Metálicas - MMSA	99,88	99,88	Production and sale of cans and related activities
Companhia de Embalagens Metálicas - MTM	99,88	99,88	Production and sale of cans and related activities
CSN Productos Siderúrgicos S.L.	100,00	100,00	Financial transactions, product sales and Equity interests
Stalhwerk Thüringen GmbH	100,00	100,00	Production and sale of long steel and related activities
CSN Steel Sections Polska Sp.Z.o.o	100,00	100,00	Financial transactions, product sales and Equity interests
CSN Mining Holding, S.L.U.	69,01	69,01	Financial transactions, product sales and Equity interests
CSN Mining GmbH	69,01	69,01	Financial transactions, product sales and Equity interests
CSN Mining Asia Limited	69,01	69,01	Commercial representation
Lusosider Ibérica S.A.	100,00	100,00	Steel, commercial and industrial activities and equity interests
Companhia Siderúrgica Nacional, LLC	100,00	100,00	Import and distribution/resale of products
Elizabeth Cimentos S.A.	99,99	99,99	Cement manufacturing
Santa Ana Energética S.A.	99,99	99,99	Electric power generation
Topázio Energética S.A.	99,99	99,99	Electric power generation
Brasil Central Energia Ltda.	99,99	99,99	Electric power generation
Circula Mais Serviços de Intermediação Comercial S.A.	99,90	99,90	Commercial intermediation for the purchase and sale of assets and materials in general
Metalgráfica Iguaçu S.A	99,89	99,89	Metal packaging manufacturing
Companhia Energética Chapecó	69,01	69,01	Electric power generation
Companhia Estadual de Geração de Energia Elétrica - CEEE-G	100,00	100,00	Electric power generation
Ventos de Vera Cruz S.A.	99,99	99,99	Electric power generation
Ventos de Curupira S.A	99,99	99,99	Electric power generation
Ventos de Povo Novo S.A.	99,99	99,99	Electric power generation
MAZET Maschinenbau und Zerspanungstechnik Unterwellwnborn GmbH	100,00	100,00	Production and sale of long steel and related activities
CSN ITC Solutions AG ⁽¹⁾	55,20		Financial transactions, product sales and Equity interests
CSN Mining International GmbH	69,01	69,01	Commercial and representation of products
Gramperfil S.A. ⁽²⁾	90,00		Manufacturing and sale of metal profile
CSN International Steel GmbH	100,00	100,00	Commercial and representation of products
Tora Transportes Ltda ⁽⁵⁾	70,00		Road transport
Tora Locações S.A. ⁽⁵⁾	70,00		Road transport and automobile rental
FJX Transportes S.A. ⁽⁵⁾	42,00		Road transport and logistic
N. Minas Transportes e Locações Ltda. ⁽⁵⁾	70,00		Road transport and logistic
Saratoga Transportes Ltda ⁽⁵⁾	70,00		Road transport
Lokamig Rent a Car S.A.⁽⁵⁾	70,00		Automobile rental
Seminovos Lokamig Ltda. ⁽⁵⁾	70,00		Automobile rental
Tora Logística Armazéns e Terminais Multimodais S.A. ⁽⁵⁾	70,00		Logistics
Tora Recintos Alfandegários S.A. ⁽⁵⁾	70,00		General storage operations and road transport
Tora Seminovos Comércio de Veículos Ltda. ⁽⁵⁾	70,00		Commercial and automobile rental
CSN Captive Insurance Company, LLC ⁽⁶⁾	100,00		Captive Insurance Company

EXPLANATORY NOTES TO THE INTERIM INFORMATION

(In thousands of reals, unless stated otherwise)

Direct interest in joint operations
Itá Energética S.A.	48,75	48,75	Electric power generation

Direct interest in joint ventures: equity method
MRS Logística S.A.	18,75	18,75	Railroad transportation
Aceros Del Orinoco S.A. (*)	31,82	31,82	Dormant company
Transnordestina Logística S.A. (7)	48,53	48,03	Railroad logistics
Equimac S.A	50,00	50,00	Rental of commercial and industrial machinery and equipment

Indirect interest in joint ventures: equity method
MRS Logística S.A.	12,93	12,93	Railroad transportation

Direct interest in associates: equity method
Arvedi Metalfer do Brasil S.A.	20,00	20,00	Metallurgy and Equity interests
Panatlântica S.A.	29,92	29,92	Steel

Indirect interest in affiliates: equity method
Jaguari Energética S.A.	10,50	10,50	Electric power generation
Chapecoense Geração S.A.	9,00	9,00	Electric power generation
Companhia Energética Rio das Antas - Ceran	30,00	30,00	Electric power generation
Foz Chapecó Energia S.A.	9,00	9,00	Electric power generation

Exclusive funds: full consolidation
Diplic II - Private credit balanced mutual fund	100,00	100,00	Investment fund
Caixa Vértice - Private credit balanced mutual fund	100,00	100,00	Investment fund
VR1 - Private credit balanced mutual fund	100,00	100,00	Investment fund

Consortiuns
Consórcio Itaúba ⁽³⁾	99,99	100,00	Electric power generation
Consórcio Passo Real ⁽⁴⁾	96,55	100,00	Electric power generation
Consórcio da Usina Hidrelétrica de Igarapava	17,92	17,92	Electric power generation
Consórcio Dona Francisca	15,00	15,00	Electric power generation

(*) Dormant companies.

(1) CSN ITC Solutions AG ("CSN ITC") was incorporated on March 5, 2025. The Company holds 55.2% of CSN ITC shares through its indirect subsidiary CSN Mining International GmbH, which holds an 80% stake in CSN ITC. Located in Switzerland, the entity is constituted as a corporation. CSN ITC's activities consist of selling, distributing and processing iron ore and related products in key strategic expansion markets, with the objective of adding value to these products. It has been exploring and seeking out business opportunities in Switzerland or other countries;

(2) Gramperfil S.A. was acquired for the total amount of EUR 11,801 on March 23, 2025. The entirety of its share capital is held by CSN Steel S.L., which is located in Portugal and constituted as a corporation. Gramperfil S.L’s business activities consist of producing, selling and transforming metal profiles and accessories, in addition to importing and exporting profiles and accessories for metal and civil construction;

(3) The 1st amendment to Consórcio Itaúba’s incorporation agreement was made on March 21, 2025, through which the equity interest held by consortium members was redistributed. CSN now holds a 39.03% state in the company, and CSN Cimentos holds 60.97% of its shares;

(4) The 1st amendment to the Passo Real consortium’s incorporation agreement was made on March 21, 2025, through which there was a change in equity interest among consortium members. CSN's stake in the company increased from 46.97% to 56.40%; Elizabeth Cimentos S.A.’s stake increased from 28.18% to 24.14%. CSN Mineração S.A. came to hold 11.09% of Passo Real’s shares, and Minérios Nacional S.A. maintained its stake at 1.56%. Additionally, the following new consortium members joined the company: Companhia Metalúrgica Prada, with 3.36% of shares, Metalgráfica Iguaçu S.A., with 0.34% of shares, and Estanho de Rondônia S.A., with a 3.11% stake.

(5) On April 1, 2025, CSN acquired shares representing 70% of Estrela Comércio e Participações S.A.’s ("Estrela”) share capital. Whereas Estrela holds an equity interest in the companies: Tora Transportes Ltda., Tora Locações S.A., FJX Transportes S.A., N. Minas Transportes e Locações Ltda., Saratoga Transportes Ltda., Lokamig Rent a Car S.A., Seminovos Lokamig Ltda., Tora Logística Armazéns e Terminais Multimodais S.A., Tora Recintos Alfandegários S.A. and Tora Seminovos Comércio de Veículos Ltda., these companies became part of the series of companies indirectly controlled by CSN.

(6) On July 8, 2025, an insurance company was incorporated under the trade name CSN Captive Insurance Company, LLC, which is located in the State of Vermont, in the United States of America.

(7) On May 16, 2025, the increase in Transnordestina Logística S.A.’s capital ("TLSA") through the issuance of new shares and partial capitalization of credits arising from AFACs held by CSN against TLSA was approved, resulting in a contribution in the amount of R$ 792,579. CSN now holds 48.53% of TLSA’s share capital on the payment date of August 22, 2025.

EXPLANATORY NOTES TO THE INTERIM INFORMATION

(In thousands of reals, unless stated otherwise)

9.a)

Changes in investments in controlled companies, jointly controlled companies, joint operations, associates, and other investments

The positions presented as of September 30, 2025, and the changes refer to the interest held by CSN in these companies:

							Consolidated
Companies	Final balance on 12/31/2024	Capital increase and (Decrease)/acquisition of shares	Dividends	Equity Income	Comprehensive income	Others	Final balance on 09/30/2025


Investments under the equity method
Joint-venture, Joint-operation and Affiliate
MRS Logistica	2,799,168			459,513	16		3,258,697
Fair Value MRS	480,622						480,622
Fair Value MRS amortization	(105,719)			(8,808)			(114,527)
Transnordestina Logística S.A. ⁽¹⁾	1,137,345	792,579		(15,856)	(261)		1,913,807
Fair Value -Transnordestina	659,106						659,106
Arvedi Metalfer do Brasil S.A.	35,257			394			35,651
Panatlântica S.A.	225,764		(6,014)	11,752			231,502
Equimac S.A	31,733		(2,187)	6,261			35,807
Indirect interest in affiliates - CEEE-G	146,753		(32,971)	27,205			140,987
Fair Value indirect participation CEEE-G	319,709						319,709
Fair Value amortization indirect participation CEEE-G	(42,523)			(13,940)			(56,463)
	5,687,215	792,579	(41,172)	466,521	(245)		6,904,898
Other participations
Others ⁽²⁾	58,796					212	59,008
	58,796					212	59,008

Total shareholdings	5,746,011	792,579	(41,172)	466,521	(245)	212	6,963,906

Classification of investments in the balance sheet
Equity interests	5,746,011						6,963,906
Investment Property	202,040						199,103
Total investments in the asset	5,948,051						7,163,009

(1) Payment of AFACs made on August 31, 2025 by CSN.

(2) Strategic investments in startups made by the subsidiary CSN Inova Ventures in the following companies: Alinea Health Holdings Ltda., I.Systems Automação Industrial S.A., 2D Materials Pte. Ltd., H2Pro Ltd., 1S1 Energy Inc., Traive Inc., Oico Holdings Ltda. and Global Dot Com S.A.

The reconciliation of the equity method results of jointly controlled entities classified as joint ventures and affiliates and the amount presented in the income statement is presented below, as well as profit and loss stemming from the elimination of CSN’s transactions with these companies:

		Consolidated
	09/30/2025	09/30/2024
	09/30/2025	09/30/2024
Equity in results of affiliated companies
MRS Logística S.A.	459,513	385,676
Transnordestina Logística S.A.	(15,856)	(16,385)
Arvedi Metalfer do Brasil S.A.	394	(302)
Equimac S.A	6,261	5,596
Indirect interest in affiliates - CEEE-G	27,205	22,200
Panatlântica S.A.	11,752	6,830
Fair Value Amortization	(22,748)	(22,775)
	466,521	380,840
Reclassification IAS 28 ⁽¹⁾	(64,683)	(66,676)
Others	16	140
Equity in results	401,854	314,304

(1) The operating margin for intercompany operations with group companies classified as joint ventures, which are not consolidated, is reclassified in the Investment group’s Income Statement under groups of costs and income tax and social contributions.

EXPLANATORY NOTES TO THE INTERIM INFORMATION

(In thousands of reals, unless stated otherwise)

Below is the reconciliation of the Parent Company's investment:

							Parent Company
Companies	Final balance on 12/31/2024	Capital increase and (Decrease)/acquisition of shares	Dividends	Equity Income	Comprehensive income	Others	Final balance on 09/30/2025


Investments under the equity method
Subsidiaries
CSN Steel S.L.U.	4,618,406			(88,248)	(90,149)		4,440,009
Sepetiba Tecon S.A.	302,152			(13,527)			288,625
Minérios Nacional S.A.	90,578	22,500		(108,806)			4,272
Fair Value - Minérios Nacional	2,122,071						2,122,071
Companhia Metalúrgica Prada	181,686			(77,532)			104,154
Goodwill - Companhia Metalúrgica Prada	63,509						63,509
CSN Mineração S.A.	7,086,794		(905,941)	314,041	473,419		6,968,313
CSN Energia S.A.	20,142			2,178			22,320
FTL - Ferrovia Transnordestina Logística S.A.	100,314			(26,932)			73,382
Companhia Florestal do Brasil	1,246,403	1,600		(23,986)	395		1,224,412
CBSI - Companhia Brasileira de Serviços de Infraestrutura	84,226			58,799			143,025
Goodwill - CBSI - Companhia Brasileira de Serviços de Infraestrutura	15,225						15,225
CSN Cimentos Brasil S.A.	6,612,579			190,681			6,803,260
Estrela Comércio e Participações S.A		168,826		(5,879)			162,947
Goodwill - Estrela Comércio e Participações S.A ⁽¹⁾		583,667					583,667
NORDESTE LOGÍSTICA S.A		3,108		(102)			3,006
CSN CAPTIVE INSURANCE COMPANY LLC ⁽²⁾		4,550					4,550
Others	313	21		15		(4)	345
	22,544,398	784,272	(905,941)	220,702	383,665	(4)	23,027,092
Joint-venture, Joint-operation and Affiliate
Itá Energética S.A.	177,351		(1,750)	10,385			185,986
MRS Logística S.A.	1,400,002			229,828	8		1,629,838
Transnordestina Logística S.A. ⁽³⁾	1,137,345	792,579		(15,856)	(261)		1,913,807
Fair Value -Transnordestina	659,106						659,106
Equimac S.A	31,733		(2,187)	6,261			35,807
Panatlântica S.A.	225,764		(6,014)	11,752			231,502
Arvedi Metalfer do Brasil S.A.	35,257			394			35,651
	3,666,558	792,579	(9,951)	242,764	(253)		4,691,697
Other participations
Profits on subsidiaries' inventories	(53,731)			36,771			(16,960)
Other investments	40						40
	(53,691)			36,771			(16,920)

Total shareholdings	26,157,265	1,576,851	(915,892)	500,237	383,412	(4)	27,701,869

Subsidiaries with unsecured liabilities
CSN Islands VII Corp.	(3,255,338)			364,239			(2,891,099)
CSN Inova Ventures	(3,348,913)			139,141			(3,209,772)
CSN Islands XII Corp.	(4,803,727)			253,521			(4,550,206)
Estanho de Rondônia S.A.	(47,190)	55,500		(71,042)			(62,732)
Others	(3,645)	2,982		(8,943)			(9,606)
Total subsidiaries with unsecured liabilities	(11,458,813)	58,482		676,916			(10,723,415)

Equity Income				1,177,153

Classification of investments in the balance sheet
Equity interests	26,157,265						27,701,869
Investment Property	135,557						133,939
Total active investments	26,292,822						27,835,808
Provision for Investments with Unsecured Liabilities (liabilities)	(11,458,813)						(10,723,415)
Total active and passive investments	14,834,009						17,112,393

EXPLANATORY NOTES TO THE INTERIM INFORMATION

(In thousands of reals, unless stated otherwise)

(2) On August 29, 2025, the Company paid in capital in its subsidiary CSN Captive Insurance Company LLC. CSN Captive Insurance Company LLC., which is located in the United States, is incorporated as a limited liability company and seek to operate in the insurance market, providing insurance coverage to the Group and third parties.

(3) Paying in of AFACs by CSN August 31, 2025.

9.b)

Investments in joint ventures and joint operations

Balance sheet and income statement at companies subject to shared control are shown below and refer to 100% of the companies' profit or loss:

				09/30/2025				12/31/2024
	Joint-Venture			Joint-Operation	Joint-Venture			Joint-Operation
Equity interest (%)	MRS Logística	Transnordestina Logística	Equimac S.A.	Itá Energética	MRS Logística	Transnordestina Logística	Equimac S.A.	Itá Energética
Equity interest (%)	37.49%	48.53%	50.00%	48.75%	37.49%	48.03%	50.00%	48.75%
Balance sheet
Current Assets
Cash and cash equivalents	4,338,229	1,416,573	14,760	128,111	4,147,393	277,966	22,028	82,129
Advances to suppliers	49,550	49,920	35	495	42,649	45,512	49	395
Other assets	1,106,334	80,105	32,145	25,578	1,182,598	83,348	25,070	27,251
Total current assets	5,494,113	1,546,598	46,940	154,184	5,372,640	406,826	47,147	109,775
Non-current Assets
Other assets	897,196	138,356	259	9,586	448,946	143,562	142	10,144
Investments, PP&E and intangible assets	16,349,788	14,685,188	79,413	240,815	14,791,500	13,193,728	75,782	263,998
Total non-current assets	17,246,984	14,823,544	79,672	250,401	15,240,446	13,337,290	75,924	274,142
Total Assets	22,741,097	16,370,142	126,612	404,585	20,613,086	13,744,116	123,071	383,917

Current Liabilities
Borrowings and financing	1,014,785	58,600	18,836		547,803	36,181	19,009
Lease liabilities	603,854		257		738,978		288
Other liabilities	1,851,737	241,430	17,100	17,889	2,103,399	128,528	16,642	15,664
Total current liabilities	3,470,376	300,030	36,193	17,889	3,390,180	164,709	35,939	15,664
Non-current Liabilities
Borrowings and financing	8,269,864	9,664,912	15,151		7,524,173	7,943,354	21,074
Lease liabilities	1,030,481		213		1,158,058		213
Other liabilities	1,278,781	2,461,627	3,439	5,187	1,074,757	3,268,493	2,379	4,457
Total non-current liabilities	10,579,126	12,126,539	18,803	5,187	9,756,988	11,211,847	23,666	4,457
Shareholders’ equity	8,691,595	3,943,573	71,616	381,509	7,465,918	2,367,560	63,466	363,796
Total liabilities and shareholders’ equity	22,741,097	16,370,142	126,612	404,585	20,613,086	13,744,116	123,071	383,917

				01/01/2025 to 09/30/2025				01/01/2024 to 09/30/2024
	Joint-Venture			Joint-Operation		Joint-Venture		Joint-Operation
Equity interest (%)	MRS Logística	Transnordestina Logística	Equimac S.A.	Itá Energética	MRS Logística	Transnordestina Logística	Equimac S.A.	Itá Energética
Equity interest (%)	37.49%	48.53%	50.00%	48.75%	37.49%	48.03%	50.00%	48.75%
Statements of Income
Net revenue	5,636,531		62,797	155,138	5,414,307		53,334	138,022
Cost of sales and services	(2,987,024)		(35,236)	(79,499)	(2,873,611)		(28,332)	(87,801)
Gross profit	2,649,507		27,561	75,639	2,540,696		25,002	50,221
Operating (expenses) income	(435,026)	(41,543)	(4,434)	(54,574)	(298,594)	(24,336)	(5,036)	(58,124)
Financial income (expenses), net	(526,425)	8,329	(3,182)	6,471	(716,275)	(9,771)	(1,944)	3,200
Profit/(Loss) before IR/CSLL	1,688,056	(33,214)	19,945	27,536	1,525,827	(34,107)	18,022	(4,703)
Current and deferred IR/CSLL	(462,432)		(6,251)	(6,232)	(492,103)		(5,804)	(637)
Profit / (loss) for the period	1,225,624	(33,214)	13,694	21,304	1,033,724	(34,107)	12,218	(5,340)

EXPLANATORY NOTES TO THE INTERIM INFORMATION

(In thousands of reals, unless stated otherwise)

9.c)

Investment properties

The balance of investment properties is shown below:

				Consolidated			Parent Company
	Ref.	Land	Buildings	Total	Land	Buildings	Total
Balance at December 31, 2024		156,858	45,182	202,040	94,257	41,300	135,557
Cost		156,858	83,285	240,143	94,257	74,389	168,646
Accumulated depreciation			(38,103)	(38,103)		(33,089)	(33,089)
Balance at December 31, 2024		156,858	45,182	202,040	94,257	41,300	135,557
Depreciation	24		(2,937)	(2,937)		(1,618)	(1,618)
Balance at September 30, 2025		156,858	42,245	199,103	94,257	39,682	133,939
Cost		156,858	83,285	240,143	94,257	74,389	168,646
Accumulated depreciation			(41,040)	(41,040)		(34,707)	(34,707)
Balance at September 30, 2025		156,858	42,245	199,103	94,257	39,682	133,939

The last estimate made by the Company's Management, with a base date of December 31, 2024, indicated amounts of R$ 2,431,581 in the consolidated statement and R$ 2,306,478 in the Parent Company -- amounts that remain unchanged on September 30, 2025.

The estimated average useful lives for the periods are as follows (in years):

		Consolidated		Parent Company
	09/30/2025	12/31/2024	09/30/2025	12/31/2024
Buildings	28	28	30	30

10.

PROPERTY, PLANT AND EQUIPMENT

10.a)

Composition of property, plant and equipment

									Consolidated
	Ref.	Land	Buildings and Infrastructure	Machinery, equipment and facilities	Furniture and fixtures	Construction in progress (*)	Right of use	Other (**)	Total
Balance at December 31, 2024		592,716	4,772,512	17,969,066	105,055	5,881,336	756,814	348,524	30,426,023
Cost		592,716	9,664,220	43,110,825	372,094	5,881,336	1,269,089	922,119	61,812,399
Accumulated depreciation			(4,891,708)	(25,141,759)	(267,039)		(512,275)	(573,595)	(31,386,376)
Balance at December 31, 2024		592,716	4,772,512	17,969,066	105,055	5,881,336	756,814	348,524	30,426,023
Effect of foreign exchange differences		(4,078)	(4,930)	(5,814)	(1,024)	(5,506)	(6,696)	(1,792)	(29,840)
Acquisitions		10,360	2,899	401,078	8,582	3,374,446	69,287	93,747	3,960,400
Capitalized interest	26					290,626			290,626
Write-offs	25		(6,110)	(20,088)	(13)	(56)	(10,027)	(159)	(36,452)
Depreciation	24		(257,642)	(2,391,668)	(14,482)		(206,393)	(80,364)	(2,950,549)
Transfers to other asset categories		14,763	151,993	2,218,745	53,233	(2,446,329)		7,595
Transfer between groups - intangible assets, investment property and inventory ⁽¹⁾				(52,946)		(34,811)			(87,757)
Right of use - Remeasurement							175,809		175,809
Acquisition of a subsidiary abroad ⁽²⁾		5,391	19,269	5,159					29,817
Impact from acquisition of shareholding in Grupo Estrela ⁽³⁾		6,963	33,350	19,984	1,230	1,550	183,929	590,134	837,140
Others								(4,485)	(4,485)
Balance at September 30, 2025		626,115	4,711,341	18,143,516	152,581	7,061,256	962,722	953,200	32,610,732
Cost		626,115	9,939,320	45,648,391	441,606	7,061,256	1,636,352	1,832,585	67,185,625
Accumulated depreciation			(5,227,979)	(27,504,875)	(289,024)		(673,630)	(879,385)	(34,574,893)
Balance at September 30, 2025		626,115	4,711,341	18,143,516	152,582	7,061,256	962,722	953,200	32,610,732

(*) Transfer to stock refers to the allocation of decommissioned or replaced vehicle assets. These assets are subsequently made available for sale by the companies Tora Seminovos Comércio de Veículos Ltda and Seminovos Lokamig Ltda, in line with the company's main commercial activities, which is the resale of used vehicles.

(**) On March 23, 2025, the Company completed the acquisition of the company Gramperfil, which is located in Portugal and constituted as a corporation. The activities of Gramperfil S.L consist of producing, selling and transforming metal profiles and accessories, in addition to importing and exposing profiles and accessories for metal and civil construction

EXPLANATORY NOTES TO THE INTERIM INFORMATION

(In thousands of reals, unless stated otherwise)

									Parent Company
	Ref.	Land	Buildings and Infrastructure	Machinery, equipment and facilities	Furniture and fixtures	Construction in progress (*)	Right of use	Others (**)	Total
Balance at December 31, 2024		25,618	328,915	7,229,728	11,471	1,984,214	37,582	46,885	9,664,413
Cost		25,618	600,505	18,210,106	106,548	1,984,214	48,227	175,734	21,150,952
Accumulated depreciation			(271,590)	(10,980,378)	(95,077)		(10,645)	(128,849)	(11,486,539)
Balance at December 31, 2024		25,618	328,915	7,229,728	11,471	1,984,214	37,582	46,885	9,664,413
Acquisitions				208,754	368	1,371,372		82	1,580,576
Capitalized interest	26					158,926			158,926
Write-offs	25			11,427					11,427
Depreciation	24		(23,521)	(1,014,512)	(2,153)		(8,108)	(9,747)	(1,058,041)
Transfers to other asset categories			69,660	1,214,816	2,303	(1,296,955)		10,176
Transfers to intangible assets						(11,006)			(11,006)
Right of use - Remeasurement							6,280		6,280
Others				(166)					(166)
Balance at September 30, 2025		25,618	375,054	7,650,047	11,989	2,206,551	35,754	47,396	10,352,409
Cost		25,618	670,165	19,645,103	109,220	2,206,551	49,065	186,011	22,891,733
Accumulated depreciation			(295,111)	(11,995,056)	(97,231)		(13,311)	(138,615)	(12,539,324)
Balance at September 30, 2025		25,618	375,054	7,650,047	11,989	2,206,551	35,754	47,396	10,352,409

(*) Highlights of Consolidated projects advancement include: (i) business expansion, mainly port expansion in Itaguaí and Casa de Pedra, Itabirito project and tailings recovery; (ii) new integrated cement plant projects; (iii) capitalized interest added during the period. At the Parent Company: (iv) comprehensive overhaul of blast furnace and coke batteries at the Presidente Vargas Plant.

(**) Refer substantially to assets classified as vehicles and hardware.

The estimated average useful lives are as follows (in years):

		Consolidated		Parent Company
	09/30/2025	12/31/2024	09/30/2025	12/31/2024
Buildings and Infrastructure	32	33	27	28
Machinery, equipment and facilities	17	17	18	18
Furniture and fixtures	10	10	12	12
Others	11	10	10	10

10.b)Right

of use

Below are the changes right of use:

					Consolidated
	Land	Buildings and Infrastructure	Machinery, equipment and facilities	Others	Total
Balance at December 31, 2024	537,008	83,112	114,612	22,082	756,814
Cost	655,481	150,311	360,925	102,372	1,269,089
Accumulated depreciation	(118,473)	(67,199)	(246,313)	(80,290)	(512,275)
Balance at December 31, 2024	537,008	83,112	114,612	22,082	756,814
Effect of foreign exchange differences		(5,764)	185	(1,118)	(6,696)
Impact from acquisition of shareholding in Grupo Estrela ⁽¹⁾				183,929	183,929
Addition	5,906	1,826	58,950	2,606	69,287
Remeasurement	26,769	1,352	110,315	37,372	175,809
Depreciation	(31,418)	(13,473)	(128,459)	(33,042)	(206,393)
Write-offs			(10,027)		(10,027)
Balance at September 30, 2025	538,265	67,053	145,576	211,829	962,722
Cost	684,951	142,668	398,960	409,773	1,636,352
Accumulated depreciation	(146,686)	(75,615)	(253,384)	(197,944)	(673,630)
Balance at September 30, 2025	538,265	67,053	145,576	211,829	962,722

(1) Transaction related to the acquisition of equity interest in the Estrela Comércio e Participações S.A. group, which entered into effect on April 1, 2025. According to CPC 15 (R1) – Business combination, the Company has one year, as of this date, to form the respective business combination, which may impact the recorded fair value within this period based on an appraisal report.

EXPLANATORY NOTES TO THE INTERIM INFORMATION

(In thousands of reals, unless stated otherwise)

				Parent Company
	Land	Machinery, equipment and facilities	Others	Total
Balance at December 31, 2024	37,394	188		37,582
Cost	43,969	2,567	1,691	48,227
Accumulated depreciation	(6,575)	(2,379)	(1,691)	(10,645)
Balance at December 31, 2024	37,394	188		37,582
Remeasurement	5,211	669	400	6,280
Depreciation	(6,960)	(748)	(400)	(8,108)
Balance at September 30, 2025	35,645	109		35,754
Cost	46,123	851	2,091	49,065
Accumulated depreciation	(10,478)	(742)	(2,091)	(13,311)
Balance at September 30, 2025	35,645	109		35,754

11.

INTANGIBLE ASSETS

								Consolidated		Parent Company
	Ref.	Goodwill	Customer relationships	Software	Trademarks and patents	Rights and licenses (*)	Others	Total	Software	Total
Balance at December 31, 2024		4,126,255	40,239	114,000	252,428	5,902,886	2,283	10,438,091	68,070	68,070
Cost		4,675,302	858,748	389,604	256,085	6,384,805	2,283	12,566,827	217,832	217,832
Accumulated amortization		(549,047)	(818,509)	(275,604)	(3,657)	(481,919)		(2,128,736)	(149,762)	(149,762)
Balance at December 31, 2024		4,126,255	40,239	114,000	252,428	5,902,886	2,283	10,438,091	68,070	68,070
Effect of foreign exchange differences			(177)	(5,081)	(6,586)			(11,844)
Acquisitions				2,001				2,001
Transfer between groups - fixed assets				34,810				34,810	11,006	11,006
Amortization	24		(3,794)	(26,612)	(12)	(104,393)		(134,811)	(14,419)	(14,419)
Transfers to other asset categories			(19,067)	23,408	(36)	(2,033)	(2,272)
Impact from acquisition of shareholding in Grupo Estrela ⁽¹⁾		22,948	11,684	952	45,280			80,864
Goodwill - Estrela Comércio e Participações S.A ⁽¹⁾		583,668						583,668
Others						954		954
Balance at September 30, 2025		4,732,871	28,885	143,478	291,074	5,797,414	11	10,993,733	64,657	64,657
Cost		5,281,918	851,960	424,716	294,743	6,383,594	11	13,236,942	228,838	228,838
Accumulated amortization		(549,047)	(823,075)	(281,238)	(3,669)	(586,180)		(2,243,209)	(164,181)	(164,181)
Balance at September 30, 2025		4,732,871	28,885	143,478	291,074	5,797,414	11	10,993,733	64,657	64,657

Composed mainly of: (i) mining rights amortized by production volume and (ii) Concession contract for hydroelectric resource utilization in acquiring control of Companhia Estadual de Geração de Energia Elétrica, with amortization performed over the contract's term.

(1) Transaction related to the acquisition of equity interest in Estrela Comércio e Participações S.A. group, which entered into effect on April 1, 2025. According to CPC 15 (R1) – Business combination, the Company has one year, as of this date, to form the respective business combination, which may impact the recorded fair value within this period based on an appraisal report.

The estimated average useful lives are as follows (in years):

		Consolidated		Parent Company
	09/30/2025	12/31/2024	09/30/2025	12/31/2024
Software	8	8	9	9
Customer relationships	13	13

EXPLANATORY NOTES TO THE INTERIM INFORMATION

(In thousands of reals, unless stated otherwise)

12.

LOANS, FINANCING AND BONDS (“DEBTS”)

The balances of loans, financing and bonds that are recorded at amortized cost are as follows:

				Consolidated			Parent Company
	Current Liabilities		Non-current Liabilities		Current Liabilities		Non-current Liabilities
	09/30/2025	12/31/2024	09/30/2025	12/31/2024	09/30/2025	12/31/2024	09/30/2025	12/31/2024

Foreign Debt
Floating Rates:
Prepayment	3,020,103	2,331,452	5,792,908	7,585,516	1,454,594	1,223,673	1,383,900	1,991,444
Fixed Rates:
Bonds, Facility and ACC	3,655,617	2,804,036	19,526,481	24,162,280	2,226,853	2,464,054	1,316,353	1,263,229
Intercompany					231,804	470,156	9,477,059	11,310,104
Fixed interest in EUR
Intercompany					12,952	351,827	341,008	-
Facility	796,581	657,980	245,602	305,556
	7,472,301	5,793,468	25,564,991	32,053,352	3,926,203	4,509,710	12,518,320	14,564,777

Debt agreements in R$
Floating Rate Securities
BNDES/FINAME/FINEP, Debentures, CRI and NCE	1,486,071	3,109,090	18,316,638	16,602,668	1,025,690	715,567	10,057,025	10,602,270
	1,486,071	3,109,090	18,316,638	16,602,668	1,025,690	715,567	10,057,025	10,602,270
Total Borrowings and Financing	8,958,372	8,902,558	43,881,629	48,656,020	4,951,893	5,225,277	22,575,345	25,167,047
Transaction Costs and Issue Premiums	(106,360)	(80,879)	(586,691)	(563,078)	(25,320)	(24,103)	(112,721)	(122,581)
Total Borrowings and Financing + Transaction cost	8,852,012	8,821,679	43,294,938	48,092,942	4,926,573	5,201,174	22,462,624	25,044,466

12.a)

Debt changes

The following table shows the reconciliation of the book value at the beginning and end of the period:

			Consolidated		Parent Company
	Ref.	09/30/2025	12/31/2024	09/30/2025	12/31/2024
Opening balance		56,914,621	44,859,075	30,245,640	23,691,305
New debts		10,072,906	10,180,554	2,342,882	7,352,398
Repayment		(10,427,054)	(6,927,383)	(2,964,791)	(5,295,236)
Payments of charges		(3,056,397)	(4,052,226)	(1,326,124)	(1,787,615)
Accrued charges	26	3,224,408	4,230,413	1,535,615	1,869,794
Impact from acquisition of shareholding in Grupo Estrela ⁽¹⁾		629,856
Iron ore prepayment ⁽²⁾		66,716
Amortization of iron ore prepayments ⁽²⁾		(66,716)
Others ⁽³⁾		(5,211,390)	8,624,188	(2,444,025)	4,414,994
Closing balance		52,146,950	56,914,621	27,389,197	30,245,640

(2) They refer to iron ore prepayment bonds that were initially recognized as contract liabilities, as they refer to a future obligation to deliver the product. However, given the impossibility of delivering the product during the period and the need for a cash settlement, this obligation came to be characterized as a monetary item and was reclassified as a financial liability. Amounts were fully settled in 2025.

(3) Amounts include unrealized changes in exchange rate and inflation, as well as costs of capital raising.

EXPLANATORY NOTES TO THE INTERIM INFORMATION

(In thousands of reals, unless stated otherwise)

The Company raised and amortized debts during 2025 as shown below:

				Consolidated
				09/30/2025
Nature	New debts	Maturities	Repayment	Interest payment
Pre-Payment	2,350,399	2025 to 2035	(2,207,684)	(611,401)
Bonds, Foreign Exchange Contract and Facility	4,196,890	2025 to 2028	(4,377,355)	(1,177,363)
BNDES/FINAME/FINEP, Debentures, CRI and NCE	3,525,617	2025 to 2042	(3,842,015)	(1,267,633)
	10,072,906		(10,427,054)	(3,056,397)


				Parent Company
				09/30/2025
Nature	New debts	Maturities	Repayment	Interest payment
Pre-Payment	512,534	2032	(1,131,403)	(516,897)
Bonds and ACC	1,680,348	2025 to 2028	(1,076,795)	(170,193)
BNDES/FINAME/FINEP, Debentures, CRI and NCE	150,000	2025 to 2039	(165,024)	(623,340)
Intercompany		2025 to 2032	(591,569)	(15,694)
	2,342,882		(2,964,791)	(1,326,124)

12.b)

Maturities of debts presented in current and non-current liabilities

			Consolidated			Parent Company
			09/30/2025			09/30/2025
	In foreign currency	In national currency - R$	Total	In foreign currency	In national currency - R$	Total
Average rate	in Dollar 6.51% in Euro 3.55%	in Real 15.90%	Total	in Dollar 3.67% in Euro 3.53%	in Real 17.08%	Total
2025	1,769,305	747,508	2,516,813	300,513	584,156	884,669
2026	6,166,914	2,038,194	8,205,108	3,722,488	1,537,183	5,259,671
2027	3,761,597	3,897,832	7,659,429	1,461,594	3,243,986	4,705,580
2028	8,621,099	2,492,399	11,113,498	3,520,450	1,862,273	5,382,723
2029	498,892	1,878,495	2,377,387	1,141,352	984,546	2,125,898
2030 to 2032	12,126,408	4,923,569	17,049,977	6,298,126	1,310,321	7,608,447
After 2032	93,077	3,824,712	3,917,789		1,560,250	1,560,250
	33,037,292	19,802,709	52,840,001	16,444,523	11,082,715	27,527,238

· Covenants

The Company's debt contracts provide for compliance with certain non-financial obligations, as well as maintenance of specific performance parameters and indicators, such as the disclosure of audited financial statements according to regulatory deadlines or having early maturity declared if the net debt to EBITDA indicator reaches the levels specified in these contracts.

As of the present date, the Company is compliant with the financial and non-financial obligations (covenants) of its current contracts.

EXPLANATORY NOTES TO THE INTERIM INFORMATION

(In thousands of reals, unless stated otherwise)

13.

FINANCIAL INSTRUMENTS

13.a)

Identification and valuation of financial instruments

The Company may operate with several financial instruments, with an emphasis on cash and cash equivalents, including investments, marketable securities, accounts receivables from customers, accounts payables to suppliers and borrowings and financing. Additionally, the Company may also operate with financial derivatives, such as swap of exchange or interest and commodities and exchange derivatives.

Considering the nature of the instruments, their fair values are basically determined by the use of quotations in the capital markets in Brazil and the Mercantile and Futures Exchange. The amounts recorded in current assets and liabilities have immediate liquidity or maturity, mostly in the short term. Considering the terms and characteristics of these instruments, the carrying amounts approximate the fair values.

EXPLANATORY NOTES TO THE INTERIM INFORMATION

(In thousands of reals, unless stated otherwise)

Classification of financial instruments

							Consolidated
				09/30/2025			12/31/2024
	Ref.	Fair value through profit or loss	Measured at amortized cost	Balances	Fair value through profit or loss	Measured at amortized cost	Balances
	Ref.	Fair value through profit or loss	Measured at amortized cost	Balances	Fair value through profit or loss	Measured at amortized cost	Balances
Assets
Current
Cash and cash equivalents	3		16,526,099	16,526,099		23,310,197	23,310,197
Financial investments	4	263,792	650,285	914,077	860,591	50,787	911,378
Trade receivables	5	275,725	2,430,759	2,706,484	181,262	2,719,736	2,900,998
Dividends and interest on equity	8		208,296	208,296		201,436	201,436
Derivative financial instruments	8			92,291	152,967		152,967
Receivables - Usiminas Shares	8		236,992	236,992
Other receivables			10,744	10,744		14,264	14,264
Trading securities	8	3,236		3,236	2,947		2,947
Loans - related parties	20.a		5,028	5,028		5,315	5,315
Total		542,753	20,068,203	20,703,247	1,197,767	26,301,735	27,499,502

Non-current
Financial investments	4		24,864	24,864		169,977	169,977
Receivables - Usiminas Shares	8		150,578	150,578
Other trade receivables			72,798	72,798		1,888	1,888
Eletrobrás compulsory loan	8		73,969	73,969		51,012	51,012
Receivables by indemnity	8		775,398	775,398		790,914	790,914
Loans - related parties	20.a		2,099,921	2,099,921		1,903,028	1,903,028
Total			3,197,528	3,197,528		2,916,819	2,916,819

Total Assets		542,753	23,265,731	23,900,775	1,197,767	29,218,554	30,416,321

Liabilities
Current
Borrowings and financing	12		8,958,372	8,958,372		8,902,558	8,902,558
Lease liabilities	14		236,081	236,081		206,323	206,323
Trade payables	15		7,087,400	7,087,400		7,030,734	7,030,734
Trade payables - Forfaiting	15.a		2,182,867	2,182,867		2,902,593	2,902,593
Dividends and interest on capital	16		4,425	4,425		61,965	61,965
Concessions to be paid	16		13,350	13,350
Total			18,482,495	18,482,495		19,104,173	19,104,173

Non-current
Borrowings and financing	12		43,881,629	43,881,629		48,656,020	48,656,020
Lease liabilities	14		853,991	853,991		633,982	633,982
Trade payables	15		77,899	77,899		43,263	43,263
Derivative transactions	16	125,226		125,226	157,857		157,857
Concessions to be paid	16		78,963	78,963		78,728	78,728
Total		125,226	44,892,482	45,017,708	157,857	49,411,993	49,569,850
Total Liabilities		125,226	63,374,977	63,500,203	157,857	68,516,166	68,674,023

EXPLANATORY NOTES TO THE INTERIM INFORMATION

(In thousands of reals, unless stated otherwise)

							Parent Company
				09/30/2025			12/31/2024
	Ref.	Fair value through profit or loss	Measured at amortized cost	Balances	Fair value through profit or loss	Measured at amortized cost	Balances
	Ref.	Fair value through profit or loss	Measured at amortized cost	Balances	Fair value through profit or loss	Measured at amortized cost	Balances
Assets
Current
Cash and cash equivalents	3		700,793	700,793		5,666,618	5,666,618
Financial investments	4	263,792	632,821	896,613	860,591	34,982	895,573
Trade receivables	5		1,442,171	1,442,171		1,555,141	1,555,141
Dividends and interest on equity	8		382,048	382,048		501,267	501,267
Receivables - Usiminas Shares	8		236,992	236,992
Other receivables			4,801	4,801
Trading securities	8	3,051		3,051	2,814		2,814
Loans - related parties	20.a		5,028	5,028		5,315	5,315
Total		266,843	3,404,654	3,671,497	863,405	7,763,323	8,626,728

Non-current
Financial investments	4					142,423	142,423
Receivables - Usiminas Shares	8		150,577	150,578
Other trade receivables			71,115	71,115		1,003	1,003
Eletrobrás compulsory loan	8		71,003	71,003		48,437	48,437
Receivables by indemnity	8		775,398	775,398		773,241	773,241
Loans - related parties	20.a		3,362,373	3,362,373		$2,499,112.00	2,499,112
Total			4,430,466	4,430,467		3,464,216	3,464,216
Total Assets		266,843	7,835,120	8,101,964	863,405	11,227,539	12,090,944

Liabilities
Current
Borrowings and financing	12		4,951,893	4,951,893		5,225,277	5,225,277
Lease liabilities	14		11,136	11,136		10,229	10,229
Trade payables	15		3,638,920	3,638,920		3,596,080	3,596,080
Trade payables - Forfaiting	15.a		1,416,596	1,416,596		2,214,482	2,214,482
Dividends and interest on capital	16		6,094	6,094		6,242	6,242
Total			10,024,639	10,024,639		11,052,310	11,052,310

Non-current
Borrowings and financing	12		22,575,345	22,575,345		25,167,047	25,167,047
Lease liabilities	14		26,320	26,320		28,224	28,224
Trade payables	15		19,377	19,377		580	580
Derivative transactions	16	82,865		82,865	157,857		157,857
Total		82,865.00	22,621,042	22,703,907	157,857	25,195,851	25,353,708
Total Liabilities		82,865.00	32,645,681	32,728,546	157,857	36,248,161	36,406,018

EXPLANATORY NOTES TO THE INTERIM INFORMATION

(In thousands of reals, unless stated otherwise)

Fair value measurement

The table below shows the financial instruments recorded at fair value through profit or loss and fair value through other comprehensive income, classifying them according to the fair value hierarchy:

Consolidated			09/30/2025			12/31/2024
Consolidated	Level 1	Level 2	Balances	Level 1	Level 2	Balances
Assets
Current
Financial investments	263,792		263,792	860,591		860,591
Trade receivables, net	275,725		275,725	181,262		181,262
Derivative transactions		92,291	92,291		152,967	152,967
Trading securities	3,236		3,236	2,947		2,947
Total Assets	542,753	92,291	635,044	1,044,800	152,967	1,197,767
Liabilities
Non-current
Derivative transactions		125,226	125,226		157,857	157,857
Total Liabilities		125,226	125,226		157,857	157,857

Level 1 – Data prices quoted are in an active market for items identical to the assets and liabilities being measured.

Level 2 – Consider inputs observable in the market, such as interest rates, exchange rates, etc., but are not prices negotiated in active markets.

Level 3 - Unobservable data, the fair value of which is determined based on the company's internal assumptions, as there is no available market data. The Company has no assets or liabilities classified as level 3.

13.b)

Financial risk management

The Company uses risk management strategies, with guidance on the risks incurred on the business.

The nature and general position of financial risks are regularly monitored and managed to assess results and the financial impact on cash flow. Credit limits and the hedge quality of counterparties are also periodically reviewed.

Market risks are hedged when considered necessary to support the corporate strategy or when it is necessary to maintain the level of financial flexibility.

The Company is exposed to exchange rate, interest rate risk, market price, and credit and liquidity risk.

The Company may manage some of the risks using derivative instruments not associated with any speculative trading or short selling.

EXPLANATORY NOTES TO THE INTERIM INFORMATION

(In thousands of reals, unless stated otherwise)

Exchange rate risk

The exposure arises from the existence of assets and liabilities denominated in Dollar, since the Company's functional currency is substantially the Real and is referred to as natural exchange exposure. The net exposure is the result of the offsetting the natural exchange exposure by the instruments of hedge adopted by the Company.

The consolidated net exposure is shown below:

	09/30/2025	12/31/2024
Foreign Exchange Exposure	(Amounts in US$’000)	(Amounts in US$’000)
Cash and cash equivalents overseas	2,019,617	1,951,025
Trade receivables	223,052	58,296
Financial investments	404,277	270,038
Borrowings and financing	(6,067,339)	(5,983,492)
Trade payables	(280,717)	(284,843)
Others	(13,213)	(37,185)
Natural Gross Foreign Exchange Exposure (assets - liabilities)	(3,714,323)	(4,026,161)
Derivative transactions (¹)	4,647,052	5,098,257
	932,729	1,072,096

(*) Total notional value of derivative and non-derivative financial instruments used for exchange risk management.

The Company uses Hedge Accounting as a strategy, as well as derivative financial instruments to protect future cash flows.

Sensitivity analysis of Derivative Financial Instruments and Consolidated Foreign Exchange Exposure

The Company evaluated two different scenarios for the analysis of the exchange rate impact: Scenario 1 projects a horizon of increased currency volatility, and Scenario 2 predicts a horizon of appreciation of the Real against the Dollar. The calculation is based on the closing exchange rate on September 30, 2025, using assumptions based on a variance calculation that considers both historical exchange rate fluctuations and management’s projections.

The currencies used in the sensitivity analysis and their respective scenarios are shown below:

				09/30/2025
Currency	Exchange rate	Probable scenario	Scenario 1	Scenario 2
USD	5.3186	5.4446	5.6984	4.9673

EXPLANATORY NOTES TO THE INTERIM INFORMATION

(In thousands of reals, unless stated otherwise)

The effects on the profit or loss, considering scenarios, 1 and 2 are shown below:

					09/30/2025
Instruments	Notional amount	Risk	Probable scenario (*) R$	Scenario 1 R$	Scenario 2 R$
Cash and cash equivalents overseas	2,019,617	Dollar	254,472	766,978	(709,465)
Trade receivables	235,383	Dollar	29,658	89,390	(82,687)
Financial investments	404,277	Dollar	50,939	153,530	(142,017)
Borrowings and financing	(6,067,339)	Dollar	(764,485)	(2,304,157)	2,131,377
Trade payables	(280,717)	Dollar	(35,370)	(106,606)	98,612
Others	(13,213)	Dollar	(1,665)	(5,018)	4,642
Derivative financial instruments	4,647,052	Dollar	585,529	1,764,783	(1,632,449)
Impact on profit or loss			119,078	358,900	(331,987)

(*) The probable scenarios were calculated considering the following variations for the risks: Real x Dollar - Devaluation of the Real by 2.37% Source: Central Bank of Brazil on October 10, 2025.

ii)

Interest rate risk

This risk stems from financial investments, loans, and financing and debentures in short and long terms linked to pre-fixed and post-fixed interest rates of CDI, TJLP, SOFR, exposing these financial assets and liabilities to interest rate fluctuations as demonstrated in the sensitivity analysis chart below.

Sensitivity analysis of interest rate changes

Below, we present the sensitivity analysis to risks related to interest rates. The Company considered two different scenarios to assess the impact of variations in these rates: Scenario 1 predicts a horizon of rising interest rates, and Scenario 2 projects a reduction horizon. To carry out the calculation, the closing rates as of September 30, 2025 were considered as references based on a variance model, which considers not only historical interest rate fluctuations but also detailed management projections.

This approach allows a comprehensive and precise assessment of potential economic impacts arising from interest rate fluctuations.

			Consolidated
			09/30/2025
Interest	Probable scenario	Scenario 1	Scenario 2
CDI	14.90%	16.76%	12.97%
TJLP	8.96%	9.10%	6.13%
IPCA	5.13%	5.57%	4.46%
SOFR 6M	3.85%	5.41%	2.51%
SOFR	4.24%	4.63%	3.84%
EURIBOR 3M	2.03%	2.92%	1.78%
EURIBOR 6M	2.10%	3.01%	1.83%

EXPLANATORY NOTES TO THE INTERIM INFORMATION

(In thousands of reals, unless stated otherwise)

The effects on the profit or loss, considering scenarios, 1 and 2 are shown below:

						Impact on balances on 09/30/2025
Changes in interest rates	% p.a	Assets	Liabilities	Probable scenario (*)	Scenario 1	Scenario 2
CDI	14.90%	5,220,103	(12,713,351)	(1,116,494)	(1,256,056)	(972,173)
TJLP	8.96%		(1,013,809)	(90,837)	(92,231)	(62,171)
IPCA	5.13%		(1,243,806)	(63,807)	(69,320)	(55,421)
SOFR 6M	3.85%		(5,658,519)	(217,621)	(305,856)	(142,290)
SOFR	4.24%		(3,307,835)	(140,252)	(153,091)	(127,098)
EURIBOR 3M	2.03%		(740,248)	(15,042)	(21,623)	(13,162)
EURIBOR 6M	2.10%		(26,826)	(562)	(808)	(492)
				(1,644,616)	(1,898,984)	(1,372,806)

(*) The sensitivity analysis is based on the premise of maintaining as a probable scenario the market values as of October 10, 2025 recorded in the Company's assets and liabilities.

iii)

Market price risk

The Company is also exposed to market risks related to the volatility of commodity and input prices. In line with its risk management policy, risk mitigation strategies involving commodities may be used to reduce cash flow volatility. These mitigation strategies may incorporate derivative instruments, predominantly forward, futures, and options transactions.

Below are the price risk protection instruments, as shown in the following topics:

a) Cash flow hedge accounting – “Platts” index

To better reflect the accounting effects of the "Platts" hedge strategy on the result, CSN Mineração opted to formally designate the hedge and, consequently, adopted hedge accounting for the iron ore derivative as a hedge accounting instrument for its highly probable future iron ore sales. As a result, the mark-to-market arising from the "Platts" volatility will be temporarily recorded in equity and will be taken to the income statement when the sales occur according to the contracted evaluation period. This allows the recognition of "Platts" volatility on iron ore sales to be recognized at the same time.

The Company has periodically reviewed market scenarios to assess its exposure to iron ore price risk to ensure adequate coverage of market price fluctuations. This process involves

monitoring fluctuations and trends in global prices, in addition to considering economic and geopolitical factors that may impact the value of this commodity.

EXPLANATORY NOTES TO THE INTERIM INFORMATION

(In thousands of reals, unless stated otherwise)

The table below shows the profit or loss of the derivative instrument up to September 30, 2025:

				09/30/2025	09/30/2025	09/30/2024	09/30/2025	09/30/2025	09/30/2024
		Appreciation (R$)		Fair value (market)	Other operating income expenses (note 25)		Other comprehensive income	Financial income (expenses) (note 26)
Maturity	Notional	Asset position	Liability position	Amounts receivable / (payable)	Other operating income expenses (note 25)		Other comprehensive income	Financial income (expenses) (note 26)
01/01/2024 to 06/30/2024 (Settled)	Platts					452,907			19,445
03/01/2025 to 05/31/2025 (Settled)	Platts				91,112			(358)
09/01/2025 to 09/30/2025 ⁽¹⁾	Platts	332,460	(335,997)	(3,537)	(3,624)			87
10/01/2025 to 10/31/2025	Platts	1,459,808	(1,434,001)	25,807			26,235	(428)
11/01/2025 to 11/30/2025	Platts	1,835,612	(1,804,199)	31,413			31,828	(415)
12/01/2025 to 12/31/2025	Platts	1,505,685	(1,485,565)	20,120			20,334	(214)
01/01/2026 to 01/31/2026	Platts	671,806	(657,653)	14,153			14,341	(188)
02/01/2026 to 02/28/2026	Platts	205,657	(201,322)	4,335			4,362	(27)
		6,011,028	(5,918,737)	92,291	87,488	452,907	97,100	(1,543)	19,445

(1) The transaction matured on September 30, 2025 and was settled in early October 2025.

The reconciliation of the amounts related to cash flow hedge accounting - "Platts" index recorded in equity as of September 30, 2025 is demonstrated as follows:

	12/31/2024	Movement	Realization	09/30/2025
Cash flow hedge – “Platts”		184,590	(87,488)	97,100
Income tax and social contribution on cash flow hedge		(62,760)	29,747	(33,013)
Fair Value of cash flow hedge - Platts, net		121,830	(57,741)	64,087

The cash flow hedge - "Platts" index was fully effective since the contracting of derivative instruments.

To support the designations, the Company prepared formal documentation indicating how the cash flow hedge accounting designation - "Platts" index aligns with CSN's risk management objectives and strategy, identifying the protection instruments used, the hedge object, the nature of the risk to be protected, and demonstrating the expectation of high effectiveness of the designated relationships. Iron ore derivative instruments ("Platts" index) were designated in amounts equivalent to the portion of future sales, comparing the designated amounts with the expected and approved amounts in the budgets of the Management and Board.

b) Cash flow hedge accounting

Foreign Exchange Hedge

In order to better reflect the accounting effects of the foreign exchange hedging strategy in the result, CSN and its subsidiary CSN Mineração designated part of their dollar liabilities as a hedge instrument for their future exports. As a result, the exchange rate variation from designated liabilities will be temporarily recorded in shareholders' equity and will be transferred to the income statement when the respective exports occur, thus allowing the recognition of dollar fluctuations on the liability and exports to be recorded at the same time. It is emphasized that the adoption of this hedge accounting does not imply the contracting of any financial instrument.

EXPLANATORY NOTES TO THE INTERIM INFORMATION

(In thousands of reals, unless stated otherwise)

The table below presents the summary of hedging relationships as of September 30, 2025:

Designation Date	Hedging Instrument	Hedged item	Type of hedged risk	Hedged period	Exchange rate on designation	Designated amounts (US$’000)	Amortized part (USD'000)	Effect on Result (*) (R$'000)	Impact on Shareholders' equity (R$'000)
07/31/2019	Bonds and Export prepayments in US$ to third parties	Part of the highly probable future monthly iron ore exports	Foreign exchange - R$ vs. US$ spot rate	January 2020 - April 2026	3.7649	1,342,761	(871,761)		(731,793)
1/10/2020	Bonds	Part of the highly probable future monthly iron ore exports	Foreign exchange - R$ vs. US$ spot rate	March 2020 to November 2025 until December 2050	4.0745	1,416,000	(1,404,000)		(1,338,043)
01/28/2020	Bonds	Part of the highly probable future monthly iron ore exports	Foreign exchange - R$ vs. US$ spot rate	March 2027 - January 2028	4.2064	1,000,000			(1,112,200)
6/1/2022	Bonds and Export prepayments in US$ to third parties	Part of the highly probable future monthly iron ore exports	Foreign exchange - R$ vs. US$ spot rate	June 2022 - April 2032	4.7289	1,145,300	(360,321)	(130,497)	(462,902)
12/1/2022	Bonds	Part of the highly probable future monthly iron ore exports	Foreign exchange - R$ vs. US$ spot rate	December 2022 - June 2031	5.0360	490,000	(37,000)		(128,018)
12/1/2022	Advance on foreign exchange contract	Part of the highly probable future monthly iron ore exports	Foreign exchange - R$ vs. US$ spot rate	December 2022 - December 2025	5.2565	100,000			(6,210)
05/16/2024	Export Prepayments in US$ with third parties, ACC and Bonds	Part of the highly probable future monthly iron ore exports	Foreign exchange - R$ vs. US$ spot rate	September 2024 - March 2035	5.1270	1,202,000	(248,400)	(71,590)	(182,710)
6/6/2024	Advance on foreign exchange contract	Part of the highly probable future monthly iron ore exports	Foreign exchange - R$ vs. US$ spot rate	June 2024 - February 2025	5.2700	30,000	(30,000)	(17,961)
06/25/2024	Advance on foreign exchange contract	Part of the highly probable future monthly iron ore exports	Foreign exchange - R$ vs. US$ spot rate	June 2024 - February 2025	5.4405	10,000	(10,000)	(2,853)
Total recognized at the parent company						6,736,061	(2,961,482)	(222,901)	(3,961,876)
6/1/2022	Export prepayments in US$ to third parties	Part of the highly probable future monthly iron ore exports	Foreign exchange - R$ vs. US$ spot rate	June 2022 - May 2033	4.7289	878,640	(215,609)	(55,083)	(390,989)
12/1/2022	Export prepayments in US$ to third parties	Part of the highly probable future monthly iron ore exports	Foreign exchange - R$ vs. US$ spot rate	December 2022 - June 2027	5.0360	70,000			(19,782)
05/16/2024	Export prepayments in US$ to third parties	Part of the highly probable future monthly iron ore exports	Foreign exchange - R$ vs. US$ spot rate	August 2025 - March 2035	5.1270	208,717	(81,686)	(5,039)	(24,339)
Total recognized in the consolidated						7,893,418	(3,258,777)	(283,023)	(4,396,986)

(*) The realization of cash flow hedge accounting is recognized Other operating revenue and expenses, in note 25.

The net balance of the amounts designated and already amortized in US Dollars totals US$ 4,634,641

In the hedge relationships described above, the values of the debt instruments were fully designated for equivalent portions of iron ore exports.

As of September 30, 2025, the hedge relationships established by the Company were effective, according to the prospective and retrospective tests carried out. Thus, no reversal due to ineffectiveness of cash flow hedge accounting was recorded.

c) Net investment hedge in foreign subsidiaries

The information related to the hedge of net investment abroad did not change in relation to that disclosed in the Company's financial statements as of December 31, 2024. The balance recorded on September 30, 2025 and December 31, 2024 in shareholders' equity is R$ 6,292.

EXPLANATORY NOTES TO THE INTERIM INFORMATION

(In thousands of reals, unless stated otherwise)

d) Hedge accounting transactions

The reconciliation of values related to cash flow hedge accounting recorded in shareholders' equity as of September 30, 2025, is demonstrated as follows:

				Consolidated
	12/31/2024	Movement	Realization	09/30/2025
Cash flow hedge	(8,970,450)	4,290,441	283,023	(4,396,986)
Income tax and social contribution on cash flow hedge	3,049,954	(1,458,750)	(96,228)	1,494,976
Fair Value of cash flow accounting, net taxes	(5,920,496)	2,831,691	186,795	(2,902,010)


				Parent Company
	12/31/2024	Movement	Realization	09/30/2025
Cash flow hedge	(7,612,357)	3,427,580	222,902	(3,961,875)
Income tax and social contribution on cash flow hedge	2,588,202	(1,165,377)	(75,787)	1,347,038
Fair Value of cash flow accounting, net taxes	(5,024,155)	2,262,203	147,115	(2,614,837)

iv)

Credit risks

The exposure to credit risks of financial institutions observes the parameters established in the financial policy. The Company's practice is the detailed analysis of the equity and financial situation of its customers and suppliers, the establishment of a credit limit and the permanent monitoring of its outstanding balance.

Regarding financial investments, the Company only makes investments in institutions with low credit risk assessed by credit rating agencies. Since part of the resources is invested in repurchase agreements that are backed by Brazilian government securities, there is also exposure to the credit risk of the Brazilian State.

Regarding credit risk exposure in trade and other receivables, the Company has a credit risk committee where each new customer is individually analyzed for their financial condition before credit limits and payment terms are granted. This is periodically reviewed according to the procedures specific to each business area.

Liquidity risk

It is the risk that the Company may not have sufficient net funds to honor its financial commitments as a result of the mismatch of term or volume between expected receipts and payments.

Future receipt and payment premises are established to manage cash liquidity in domestic and foreign currencies, which are monitored on a day-to-day basis by the Treasury department. The payment schedules of long-term installments of borrowings, financing and bonds are shown in note 12.

EXPLANATORY NOTES TO THE INTERIM INFORMATION

(In thousands of reals, unless stated otherwise)

The amounts represent contractual maturities for financial liabilities including interest:

						Consolidated
At September 30, 2025	Ref.	Less than one year	From one to two years	From two to five years	Over five years	Total
Loans, financing and debentures	12.b	8,958,372	9,422,979	13,490,885	20,967,765	52,840,001
Lease liabilities	14	236,081	332,708	139,496	381,787	1,090,072
Derivative financial instruments	16				125,226	125,226
Trade payables	15	7,087,400	58,355	19,158	386	7,165,299
Trade payables - Forfaiting	15.a	2,182,867				2,182,867
Dividends and interest on capital	16	4,425				4,425
Concessions to be paid	16	13,350	13,350	26,700	38,913	92,313
		18,482,495	9,827,392	13,676,239	21,514,077	63,500,203

Fair values of assets and liabilities in relation to book value

Financial assets and liabilities measured at fair value through profit or loss are recorded in current and non-current assets and liabilities and any gains and losses are recorded as financial income and expense, respectively.

The amounts are recorded in the financial statements at their book value, which are substantially similar to those that would be obtained if they were traded in the market. The fair values of other long-term assets and liabilities do not differ significantly from their carrying amounts, except for the amounts below.

The estimated fair value for certain consolidated long-term loans and financing were calculated at current market rates, considering the nature, term and risks similar to those of the registered contracts, as follows:

		09/30/2025		12/31/2024
	Closing Balance	Fair value	Closing Balance	Fair value
Fixed Rate Notes (*)	19,146,612	17,419,436	22,204,604	19,584,985

(*) Source: Bloomberg

13.c)

Protective instruments: Derivatives

Position of the derivative financial instruments portfolio

Currency swap Dollar x Euro

The subsidiary Lusosider Projectos Siderúrgicos S.A. had a derivative operation to protect its exposure to the Dollar, which was settled in November 2024.

Foreign exchange swap CDI x Dollar

In October 2023, the Company entered into a new swap agreement with the purpose of mitigating the risk associated with an External Credit Note (NCE) acquired during the same period, whose maturity is scheduled for October 2028, and which has a principal amount of R$ 680,000.

EXPLANATORY NOTES TO THE INTERIM INFORMATION

(In thousands of reals, unless stated otherwise)

In January 2025, the Company entered into a new swap agreement with the objective of protecting its foreign exchange exposure to the Dollar associated with an Export Credit Note (ECN) acquired during the same period, whose maturity is scheduled for January 2028, and which has a principal amount of R$ 295,000.

Foreign exchange swap Dollar x Real

In July 2024, the subsidiary CSN Cimentos Brasil, after raising a foreign currency loan in the amount of R$ 50,000, contracted derivative instruments ith the objective of protecting its foreign exchange exposure to the Dollar, with maturity in July 2027.

In June 2025, CSN Cimentos Brasil settled a derivative transaction, which had the objective of protecting against foreign exchange exposure to the Dollar through a foreign currency loan in the amount of R$ 115,000. This debt was paid during the same period.

Interest swap CDI x IPCA

CSN Mineração, CSN Cimentos Brasil and CSN issued debentures during the years 2021, 2022 and 2023, respectively, and contracted derivative operations to protect their exposure to IPCA. The CSN Mineração contracts have staggered maturities between 2031 and 2037; the CSN Cimentos contracts mature in 2032 and CSN’s between 2030 and 2039.

Below is the position of derivatives:

								Consolidated
							09/30/2025	09/30/2024
				Appreciation (R$)		Fair value (market)	Impact on financial income (expenses)
Instrument	Maturity	Functional Currency	Notional amount	Asset position	Liability position	Amounts receivable / (payable)	Impact on financial income (expenses)
Exchange rate swap

Exchange rate swap Dollar x Euro - Lusosider	Settled							(1,627)
Exchange rate swap CDI x Dollar - CSN	2028	Real	975,000	1,044,889	(1,127,754)	(82,865)	93,222	(66,888)
Dollar x Real swap - CSN Cimentos Brasil	2027	Dollar	50,000	283,682	(301,697)	(18,015)	(183,044)	35,928
Exchange rate swap Dollar x CDI - Grupo Estrela	2027	Dollar	41,465	227,536	(251,882)	(24,346)	(50,121)
Total Exchange rate Swap			1,066,465	1,556,107	(1,681,333)	(125,226)	(139,943)	(32,587)
Interest rate swap
Interest rate (Debentures) CDI x IPCA - CSN	2030 to 2039	Real	2,012,358	2,114,882	(2,218,923)	(104,041)	(29,540)	(76,958)
Interest rate (Debentures) CDI x IPCA - CSN Mineração	2031 to 2037	Real	2,400,000	2,647,475	(2,673,922)	(26,447)	(30,221)	(219,738)
Interest rate (Debentures) CDI x IPCA - CSN Cimentos Brasil	2032	Real	1,200,000	1,353,886	(1,281,559)	72,326	(15,851)	(93,944)
Total interest rate (Debentures) CDI x IPCA			5,612,358	6,116,243	(6,174,404)	(58,162)	(75,612)	(390,639)

				7,672,350	(7,855,737)	(183,387)	(215,555)	(423,226)

EXPLANATORY NOTES TO THE INTERIM INFORMATION

(In thousands of reals, unless stated otherwise)

Classification of derivatives in the balance sheet and income statement

							09/30/2025	09/30/2024	09/30/2025	09/30/2024	09/30/2025	09/30/2024
Instruments	Assets			Liabilities			Other operating income expenses		Other comprehensive income		Financial income (expenses), net (note 26)
Instruments	Current	Non-current	Total	Current	Non-current	Total	Other operating income expenses		Other comprehensive income		Financial income (expenses), net (note 26)
Iron ore derivative	92,291		92,291				87,490	452,906	97,099		(1,543)	19,446
Exchange rate swap Dollar x Euro												(1,627)
Exchange rate swap CDI x Dollar					(107,211)	(107,211)					43,101	(66,888)
Exchange rate swap CDI x IPCA ⁽¹⁾					(58,162)	(58,162)					(75,612)	(390,639)
Dollar x Real swap					(18,015)	(18,015)					(183,044)	35,928
	92,291		92,291		(183,388)	(183,388)	87,490	452,906	97,099		(217,098)	(403,780)

(1) The SWAP CDI x IPCA derivative instruments are fully classified in the loans and financing group, since they are linked to bonds order with the purpose of protecting against IPCA exposure.

13.d)

Investments in securities measured at fair value through profit or loss

The Company holds common shares (USIM3), preferred shares (USIM5) of Usiminas Siderúrgica de Minas Gerais S.A. (“Usiminas”). Usiminas shares are classified as current assets in financial investments and at fair value, based on the market price quotation on B3.

According to the Company's policy, gains and losses resulting from changes in stock prices are recorded directly in the income statement under financial income for shares classified as financial investments and under other operating income and expenses for shares classified as investments.

Stock Market Price Risks

Class of shares	09/30/2025				12/31/2024				09/30/2025	09/30/2024
Class of shares	Quantity	Equity interest (%)	Share price	Closing Balance	Quantity	Equity interest (%)	Share price	Closing Balance	Profit or loss (note 26)
USIM3	35,192,508	4.99%	4.21	148,160	106,620,851	15.12%	5.32	567,222	(105,315)	(340,120)
USIM5	27,336,117	4.99%	4.23	115,632	55,144,456	10.07%	5.32	293,369	(60,852)	(168,191)
				263,792				860,591	(166,167)	(508,311)

The Company is exposed to the risk of changes in share prices due to investments measured at fair value through profit or loss that have their quotations based on market price on B3.

Sensitivity analysis for stock price risks

We present below the sensitivity analysis for the risks related to the stock price variation. The Company evaluated two distinct scenarios for the impact of price fluctuations: Scenario 1 (extreme optimistic) forecasts a horizon of price appreciation, and Scenario 2 (extreme pessimistic) considers a horizon of deterioration in price volatility. The calculation was based on the closing price of the shares on September 30, 2025, using assumptions based on both the dispersion of historical variations in prices and projections prepared by Management.

EXPLANATORY NOTES TO THE INTERIM INFORMATION

(In thousands of reals, unless stated otherwise)

The effects on profit or loss, considering the probable scenarios, 1 and 2, are shown below:

							09/30/2025
Class of shares	Quantity	Share price on 09/30/2025	Extreme Optimistic Scenario share price	Extreme Pessimistic Scenario share price	Closing Balance	Extreme Optimistic Scenario (1)	Extreme Pessimistic Scenario (2)

USIM3	35,192,508	4.21	4.74	2.37	148,160	18,520	(64,820)
USIM5	27,336,117	4.23	4.76	2.38	115,632	14,454	(50,589)
					263,792	32,974	(115,409)

13.e)

Capital Management

The Company seeks to optimize its capital structure with the purpose of reducing its financial costs and maximizing return to its shareholders. The following chart demonstrates the evolution of the Company's consolidated capital structure, with financing through equity and third-party capital:

Thousands of Reais	09/30/2025	12/31/2024
Shareholder's equity (equity)	17,355,367	15,459,116
Borrowings and Financing (Third-party capital)	52,146,950	56,914,621
Gross Debit/Shareholder's equity	3.00	3.68

14.

LEASE LIABILITIES

The lease liabilities are presented below:

		Consolidated		Parent Company
	09/30/2025	12/31/2024	09/30/2025	12/31/2024
Leases	2,433,277	2,122,768	44,259	46,760
Adjusted present value - Leases	(1,343,205)	(1,282,463)	(6,803)	(8,307)
	1,090,072	840,305	37,456	38,453
Classified:
Current	236,081	206,323	11,136	10,229
Non-current	853,991	633,982	26,320	28,224
	1,090,072	840,305	37,456	38,453

NATIONAL STEEL CO 6-K