UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 6-K

Report of Foreign Issuer

Pursuant To Rule 13a-16 Or 15d-16 of the

Securities Exchange Act of 1934

For the month of May 2026

Commission File Number: 333-251238

COSAN S.A.

(Exact name of registrant as specified in its charter)

N/A

(Translation of registrant’s name into English)

Av. Brigadeiro Faria Lima, 4100, – 16th floor
São Paulo, SP 04538-132 Brazil
(Address of principal executive offices)

Indicate by check mark whether the registrant files or will file annual reports under cover of Form 20-F or Form 40‑F:

Form 20-F ☒ Form 40-F ☐

Indicate by check mark if the registrant is submitting the Form 6-K in paper as permitted by Regulation S-T Rule 101(b)(1):

Yes ☐ No ☒

Indicate by check mark if the registrant is submitting the Form 6-K in paper as permitted by Regulation S-T Rule 101(b)(7):

Yes ☐ No ☒

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Table of Contents

CONTENT

Independent Auditor's Report on the Condensed Interim Individual and Consolidated Financial Statements	3
Interim statement of financial position	5
Interim statement of profit or loss	7
Interim statement of other comprehensive income	8
Interim statements of changes in equity	9
Interim statement of cash flows	11
Interim statement of value added	14
1 Operations context	15
2 Relevant events of the period	16
2.1 Investments	16
2.2 New debts	19
3 Statement of compliance and material accounting policies	20
3.1 Restatement in the statement of value added	20
4. Segment information	22
4.1 Net sales to external customers by product/customer type	27
4.2 Information on geographical area	28
5 Financial assets and liabilities	29
5.1 Cash and cash equivalents	30
5.2 Loans, borrowings and debentures	30
5.3 Derivative financial instruments	33
5.4 Related parties	41
5.5 Trade payables	44
5.6 Recognized Fair value measurement	44
5.7 Financial risk management	45
5.8 Obligation to repurchase shares of a subsidiary	48
6 Investment in subsidiaries and associates	49
6.1 Investments in subsidiaries	49
6.2 Non-controlling interest in subsidiaries	50
7 Property, plant and equipment, intangible assets, goodwill, and impairment loss	51
7.1 Property plant and equipment	51
7.2 Intangible assets and goodwill	52
7.3 Impairment loss	52
8 Income taxes	53
9 Provision for legal proceedings and judicial deposits	56
10 Shareholder's equity	59
11 Earnings per share	59
12 Net sales	60
13 Costs and expenses by nature	61
14 Other operating income (expenses), net	61
15 Financial results	62
16 Share-based payment	63
18 Subsequent events	63

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(A free translation of the original in Portuguese)

Cosan S.A.

Report on review of parent company and

consolidated condensed interim financial statements

To the Board of Directors and Stockholders

Cosan S.A.

Introduction

We have reviewed the accompanying interim statement of financial position of Cosan S.A. ("Company") as at March 31, 2026 and the related statements of profit or loss, other comprehensive income, changes in equity and cash flows for the quarter then ended, as well as the accompanying consolidated interim statement of financial position of the Company and its subsidiaries ("Consolidated") as at March 31, 2026 and the related consolidated statements of profit or loss, other comprehensive income, changes in equity and cash flows for the quarter then ended, and explanatory notes.

Management is responsible for the preparation and presentation of these parent company and consolidated condensed interim financial statements in accordance with the accounting standard CPC 21, Interim Financial Reporting, of the Brazilian Accounting Pronouncements Committee (CPC), and International Accounting Standard (IAS) 34 - Interim Financial Reporting, of the International Accounting Standards Board (IASB). Our responsibility is to express a conclusion on these condensed interim financial statements based on our review.

Scope of review

We conducted our review in accordance with Brazilian and International Standards on Reviews of Interim Financial Information (NBC TR 2410 - Review of Interim Financial Information Performed by the Independent Auditor of the Entity, and ISRE 2410 - Review of Interim Financial Information Performed by the Independent Auditor of the Entity, respectively). A review of interim financial information consists of making inquiries, primarily of persons responsible for financial and accounting matters, and applying analytical and other review procedures. A review is substantially less in scope than an audit conducted in accordance with Brazilian and International Standards on Auditing and consequently did not enable us to obtain assurance that we would become aware of all significant matters that might be identified in an audit. Accordingly, we do not express an audit opinion.

Conclusion

Based on our review, nothing has come to our attention that causes us to believe that the accompanying parent company and consolidated condensed interim financial statements referred to above are not prepared, in all material respects, in accordance with CPC 21 and IAS 34.

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(A free translation of the original in Portuguese)

Cosan S.A.

Other matters - Statements of value added

The interim condensed financial statements referred to above include the parent company and consolidated statements of value added for the quarter ended March 31, 2026. These statements are the responsibility of the Company's management and are presented as supplementary information under IAS 34. These statements have been subjected to review procedures performed together with the review of the condensed interim financial statements for the purpose of concluding whether they are reconciled with the condensed interim financial statements and accounting records, as applicable, and if their form and content are in accordance with the criteria defined in the accounting standard CPC 09 - "Statement of Value Added". Based on our review, nothing has come to our attention that causes us to believe that these condensed statements of value added have not been properly prepared, in all material respects, in accordance with the criteria established in this accounting standard, and consistent with the parent company and consolidated condensed interim financial statements taken as a whole.

São Paulo, May 14, 2026

PricewaterhouseCoopers

Auditores Independentes Ltda.

CRC 2SP000160/O-5

Alessandro Marchesino de Oliveira

Contador CRC 1SP265450/O-8

Table of Contents

Interim statement of financial position

(In thousands of Brazilian reais - R$)

		Parent Company		Consolidated
	Note	March 31, 2026	December 31, 2025	March 31, 2026	December 31, 2025
Assets
Cash and cash equivalents	5.1	6,216,620	15,383,305	17,463,977	27,243,683
Restricted cash		—	—	44,401	45,781
Marketable securities		1,236,948	23,211	3,861,478	2,588,411
Trade receivable		—	—	4,156,580	3,520,278
Derivative financial instruments	5.3	—	72,145	199,881	310,981
Inventories		—	—	1,903,484	1,969,258
Receivables from related parties	5.4	135,255	117,836	219,116	199,549
Income tax recoverable.		761,061	709,042	1,304,465	1,166,622
Other current tax receivable		5,279	5,278	966,305	1,022,881
Dividend receivable		86,320	87,224	85,759	35,410
Sectoral financial assets		—	—	415,527	338,332
Other financial assets		—	—	—	612
Other current assets		110,429	74,506	631,941	993,667
		8,551,912	16,472,547	31,252,914	39,435,465
Current assets held for sale		532,136	531,734	652,168	652,168
Current assets		9,084,048	17,004,281	31,905,082	40,087,633

Trade receivable		—	—	151,887	148,885
Marketable securities		—	307,177	77,437	404,182
Restricted cash		34	186	188,083	182,987
Deferred tax assets	8	547,618	1,378,628	2,766,337	3,703,864
Receivables from related parties	5.4	106,698	102,476	3,586	20,348
Income tax recoverable.		—	—	227,448	195,821
Other non-current tax receivable		35,937	35,278	1,966,140	1,815,830
Judicial deposits	9	352,781	351,904	1,081,122	1,072,982
Derivative financial instruments	5.3	17,706	134,239	2,003,092	1,956,127
Sectoral financial assets		—	—	407,497	390,622
Other non-current assets		101,462	128,894	1,026,558	919,706
Other financial assets		—	—	344	5,193
Investment in associates	6.1	17,101,988	16,573,858	1,711,406	1,721,308
Investment in joint ventures		11,381	11,509	56,897	60,356
Property plant and equipment	7.1	30,740	30,303	27,949,865	26,795,725
Intangible assets and goodwill	7.2	11,029	11,715	26,595,427	26,706,626
Contract assets		—	—	997,551	1,044,613
Right-of-use assets		10,922	12,649	9,650,585	9,662,929
Investment property		—	—	18,222,462	18,221,781
Non-current assets		18,328,296	19,078,816	95,083,724	95,029,885

Total assets		27,412,344	36,083,097	126,988,806	135,117,518

The accompanying notes are an integral part of the condensed interim individual and consolidated financial statements.

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Interim statement of financial position

(In thousands of Brazilian reais - R$)

		Parent Company		Consolidated
	Note	March 31, 2026	December 31, 2025	March 31, 2026	December 31, 2025
Liabilities
Loans, borrowings and debentures	5.2	483,211	481,367	3,705,268	3,918,720
Leases		9,935	9,935	982,749	982,991
Derivative financial instruments	5.3	37,460	369,813	1,694,972	1,909,404
Trade payables	5.5	2,020	870	3,812,231	4,078,511
Employee benefits payables		17,104	43,695	516,742	771,618
Income tax payables		21,408	15,369	118,944	153,310
Other taxes payable		29,168	34,951	548,833	525,208
Dividends payable		—	—	231,804	226,484
Concessions payable		—	—	189,808	189,076
Related party payables	5.4	179,669	233,562	337,775	320,916
Sectoral financial liabilities		—	—	95,797	96,719
Other financial liabilities	5	2,909,136	—	3,751,188	1,096,884
Other Trade payables		351,618	514,651	995,537	1,192,397
		4,040,729	1,704,213	16,981,648	15,462,238
Liabilities related to assets held for sale		—	—	86,138	86,138
Current liabilities		4,040,729	1,704,213	17,067,786	15,548,376

Loans, borrowings and debentures	5.2	12,006,585	15,907,024	54,796,351	60,308,411
Leases		6,033	8,210	5,392,261	5,429,809
Put option liability on subsidiary shares	5.8	3,994,832	3,844,648	3,994,832	3,844,648
Derivative financial instruments	5.3	38,275	215,820	650,002	771,265
Trade payables	5.5	—	—	19,245	18,991
Employee benefits payables		—	—	29,122	23,406
Other taxes payable		153,512	149,367	181,630	176,702
Income tax payables		5,985	5,919	99,251	78,872
Provision for legal proceedings	9	266,035	295,175	2,152,044	2,058,122
Concessions payable		—	—	3,935,070	3,799,169
Investments with uncovered liabilities	6.1	302	371,318	—	—
Related party payables	5.4	3,331,237	5,397,919	1,156	1,166
Post-employment benefits		344	386	543,292	536,426
Deferred tax liabilities	8	—	—	6,128,534	6,125,221
Sectoral financial liabilities		—	—	2,215,442	2,168,542
Other financial liabilities	5	—	2,804,606	—	2,804,606
Other non-current liabilities		74,726	74,264	392,818	414,154
Non-current liabilities		19,877,866	29,074,656	80,531,050	88,559,510

Total liabilities		23,918,595	30,778,869	97,598,836	104,107,886

Shareholders’ equity	10
Share capital		10,282,739	10,282,739	10,282,739	10,282,739
Treasury shares		(266,892)	(76,150)	(266,892)	(76,150)
Additional paid-in capital		4,180,652	4,194,210	4,180,652	4,194,210
Accumulated other comprehensive income		602,725	625,554	602,725	625,554
Accumulated losses		(11,305,475)	(9,722,125)	(11,305,475)	(9,722,125)
Equity attributable to owners of the Company		3,493,749	5,304,228	3,493,749	5,304,228
Non-controlling interests	6.2	—	—	25,896,221	25,705,404
Total shareholders' equity		3,493,749	5,304,228	29,389,970	31,009,632
Total liabilities and shareholders' equity		27,412,344	36,083,097	126,988,806	135,117,518

The accompanying notes are an integral part of the condensed interim individual and consolidated financial statements

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Interim statement of profit or loss

((In thousands of Brazilian reais - R$, excluding earnings per share)

		Parent Company		Consolidated
		Period of three months ended March, 31
	Note	2026	2025	2026	2025
Net sales	12	—	—	9,028,800	9,662,601
Cost of sales	13	—	—	(5,953,019)	(6,791,905)
Gross profit		—	—	3,075,781	2,870,696

Selling expenses	13	—	—	(443,814)	(440,056)
General and administrative expenses	13	(45,939)	(57,937)	(547,411)	(535,032)
Other operating income (expenses), net	14	(33,398)	173,925	234,949	524,130
Impairment	14	—	—	(168,104)	(285,608)
Operating expenses		(79,337)	115,988	(924,380)	(736,566)

(Loss) profit before equity in earnings of investees, finance results and income taxes		(79,337)	115,988	2,151,401	2,134,130

Interest in (losses) earnings of subsidiaries and associates	6.1	117,844	(493,236)	48,676	19,049
Interest in losses of joint ventures		(1,032)	(128,194)	(4,363)	(1,139,047)
Equity in (losses) earnings of investees		116,812	(621,430)	44,313	(1,119,998)

Finance expense		(891,006)	(763,961)	(2,848,174)	(2,713,642)
Finance income		345,462	224,542	1,016,676	1,037,901
Foreign exchange, net		281,893	1,079,284	702,518	1,793,964
Net gain (loss) on derivatives		(523,713)	(1,163,099)	(1,233,929)	(2,021,218)
Finance results, net	15	(787,364)	(623,234)	(2,362,909)	(1,902,995)

Loss before income taxes		(749,889)	(1,128,676)	(167,195)	(888,863)

Income tax	8
Current		(2,451)	—	(236,385)	(303,162)
Deferred		(831,010)	(659,219)	(941,399)	(743,373)
		(833,461)	(659,219)	(1,177,784)	(1,046,535)

Loss for the period		(1,583,350)	(1,787,895)	(1,344,979)	(1,935,398)

Loss attributable to:
Owners of the Company		(1,583,350)	(1,787,895)	(1,583,350)	(1,787,895)
Non-controlling interests		—	—	238,371	(147,503)
		(1,583,350)	(1,787,895)	(1,344,979)	(1,935,398)

Loss per share	11
Basic				R$(0.40)	R$(0.96)
Diluted				R$(0.41)	R$(0.96)

The accompanying notes are an integral part of the condensed interim individual and consolidated financial statements.

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Interim statement of other comprehensive income

(In thousands of Brazilian reais - R$)

	Parent Company		Consolidated
	Period of three months ended March, 31
	2026	2025	2026	2025
Loss for the period	(1,583,350)	(1,787,895)	(1,344,979)	(1,935,398)

Other comprehensive income:
Items that are or may be reclassified subsequently to profit or loss ⁽ⁱ⁾:
Foreign currency translation differences	(64,537)	(290,696)	(121,559)	(290,198)
Gain on Cash flows hedge	41,715	162,887	19,858	222,492
Income tax impact	—	—	(1,253)	(28,025)
	(22,822)	(127,809)	(102,954)	(95,731)

Items that will not be reclassified to profit or loss:
Remeasurement gain (loss) on defined benefit plans	15	(22,497)	33	(59,336)
Loss in fair value of financial liabilities designated at fair value through profit or loss attributable to changes in credit risk ⁽ⁱ⁾	(22)	—	(5,274)	—
Income tax impact	—	8,499	1,811	17,002
	(7)	(13,998)	(3,430)	(42,334)

Total comprehensive loss for the period	(1,606,179)	(1,929,702)	(1,451,363)	(2,073,463)

Comprehensive loss attributable to:
Owners of the Company	(1,606,179)	(1,929,702)	(1,606,179)	(1,929,702)
Non-controlling interests	—	—	154,816	(143,761)
	(1,606,179)	(1,929,702)	(1,451,363)	(2,073,463)

The accompanying notes are an integral part of the condensed interim individual and consolidated financial statements.

(i) For the Parent Company, the effects arise from the equity method of accounting for its subsidiaries

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Interim statements of changes in equity

(In thousands of Brazilian reais - R$)

			Capital reserve				Shareholders’ equity attributable to
	Share capital	Treasury shares	Corporate transactions - Law 6.404/76	Additional paid-in capital	Accumulated other comprehensive income	Accumulated losses	Controlling shareholders	Non-controlling interests	Total equity
Balance as at January 1, 2026	10,282,739	(76,150)	737	4,193,473	625,554	(9,722,125)	5,304,228	25,705,404	31,009,632

(Loss) profit for the period	—	—	—	—	—	(1,583,350)	(1,583,350)	238,371	(1,344,979)

Other comprehensive income
Gain (loss) from cash flows hedge	—	—	—	—	41,715	—	41,715	(23,110)	18,605
Foreign currency translation differences	—	—	—	—	(64,537)	—	(64,537)	(57,022)	(121,559)
Remeasurement gain on defined benefit plans, net of tax	—	—	—	—	15	—	15	18	33
Loss in fair value of financial liabilities designated at fair value tthrough profit or loss attributable to changes in credit risk	—	—	—	—	(22)	—	(22)	(3,441)	(3,463)
Total comprehensive (loss) income for the period	—	—	—	—	(22,829)	(1,583,350)	(1,606,179)	154,816	(1,451,363)

Transactions with owners of the Company contributions and distributions:
Effect arising from capital increase in subsidiary	—	—	—	—	—	—	—	1,038	1,038
Own shares acquired (note 10 (a))	—	(213,666)	—	(2,841)	—	—	(216,507)	—	(216,507)
Share-based payments	—	22,924		(22,738)	—	—	186	—	186
Dividends	—	—	—	—	—	—	—	(3,229)	(3,229)
Employee share schemes - value of employee services	—	—	—	12,080	—	—	12,080	38,192	50,272
Total contributions and distributions	—	(190,742)	—	(13,499)	—	—	(204,241)	36,001	(168,240)

Transactions with owners of the Company:
Change of shareholding interest in subsidiary and other transactions	—	—	—	(59)	—	—	(59)	—	(59)
Total transactions with owners of the Company	—	—	—	(59)	—	—	(59)	—	(59)

Total transactions with owners of the Company contributions and distributions	—	(190,742)	—	(13,558)	—	—	(204,300)	36,001	(168,299)

Balance as at March 31, 2026	10,282,739	(266,892)	737	4,179,915	602,725	(11,305,475)	3,493,749	25,896,221	29,389,970

The accompanying notes are an integral part of the condensed interim individual and consolidated financial statements.

Table of Contents

Interim statements of changes in equity

(In thousands of Brazilian reais - R$)

			Capital reserve			Profit reserves			Shareholders’ equity attributable to
	Share capital	Treasury shares	Corporate transactions - Law 6.404/76	Additional paid-in capital	Accumulated other comprehensive income	Legal	Statutory reserve	Accumulated losses	Controlling shareholders	Non-controlling interests	Total equity
Balance as at January 1, 2025	8,832,544	(50,708)	737	2,205,141	565,855	58,802	8,715,188	(9,423,795)	10,903,764	28,494,598	39,398,362

Loss for the period	—	—	—	—	—	—	—	(1,787,895)	(1,787,895)	(147,503)	(1,935,398)

Other comprehensive income
Gain from cash flows hedge	—	—	—	—	162,887	—	—	—	162,887	31,580	194,467
Foreign currency translation differences	—	—	—	—	(290,696)	—	—	—	(290,696)	498	(290,198)
Remeasurement loss on defined benefit plans, net of tax	—	—	—	—	(13,998)	—	—	—	(13,998)	(28,336)	(42,334)
Total comprehensive loss for the period	—	—	—	—	(141,807)	—	—	(1,787,895)	(1,929,702)	(143,761)	(2,073,463)

Transactions with owners of the Company:
Share-based payment	—	234	—	114	—	—	—	—	348	6,771	7,119
Dividends	—	—	—	—	—	—	—	—	—	(375,782)	(375,782)
Own shares acquired	—	(34,022)	—	—	—	—	—	—	(34,022)	—	(34,022)
Employee share schemes - value of employee services	—	—	—	15,559	—	—	—	—	15,559	2,135	17,694
Total contributions and distributions	—	(33,788)	—	15,673	—	—	—	—	(18,115)	(366,876)	(384,991)

Transactions with owners of the Company:
Change of shareholding interest in subsidiary	—	—	—	(975,200)	—	—	—	—	(975,200)	(1,193,730)	(2,168,930)
Capital reduction in subsidiary	—	—	—	(89,084)	—	—	—	—	(89,084)	89,084	—
Total transactions with owners of the Company	—	—	—	(1,064,284)	—	—	—	—	(1,064,284)	(1,104,646)	(2,168,930)

Total transactions with owners of the Company contributions and distributions	—	(33,788)	—	(1,048,611)	—	—	—	—	(1,082,399)	(1,471,522)	(2,553,921)

Balance as at March 31, 2025	8,832,544	(84,496)	737	1,156,530	424,048	58,802	8,715,188	(11,211,690)	7,891,663	26,879,315	34,770,978

The accompanying notes are an integral part of the condensed interim individual and consolidated financial statements.

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Interim statement of cash flows

(In thousands of Brazilian reais - R$)

Interim statement of cash flows

		Parent Company		Consolidated
		Period of three months ended March 31,
	Note	2026	2025	2026	2025
Cash flows from operating activities
Loss before income taxes		(749,889)	(1,128,676)	(167,195)	(888,863)
Adjustments for:
Depreciation and amortization	13	5,396	4,713	971,396	967,894
Impairment	14	—	—	168,104	285,608
Interest in (losses) earnings of subsidiaries and associates	6.1	(117,844)	493,236	(48,676)	(19,049)
Interest in earnings (losses) of joint ventures		1,032	128,194	4,363	1,139,047
Loss (gain) on disposed assets	14	—	—	(19,515)	(4,194)
Share-based payment	16	9,655	6,220	19,813	23,892
Provision for legal proceedings	14	5,138	35,589	82,202	84,992
Interest, derivatives, monetary and foreign exchange, net		928,361	762,997	2,808,860	2,397,005
Sectorial financial assets and liabilities, net		—	—	(71,274)	8,586
Provisions for employee benefits		9,368	(579)	102,918	93,871
Allowance for expected credit losses		—	—	1,138	11,110
Revenue from insurance claims		—	—	(7,114)	—
Income from finance investments		—	(9,143)	—	(9,143)
Previously recognized gain in other comprehensive income reclassified to profit		—	(206,388)	—	(206,388)
Other		(31)	10	(20,859)	(89,465)
		91,186	86,173	3,824,161	3,794,903
Variation in:
Trade receivable		—	—	(681,703)	(263,936)
Inventories		—	—	9,450	(99,705)
Other taxes, net		(52,808)	2,764	(215,891)	(382,326)
Income taxes paid		—	(26,586)	(262,697)	(371,123)
Related parties, net		(59,301)	21,633	(6,632)	(21,353)
Trade payables		1,157	(1,596)	(124,000)	(280,419)
Employee benefits		(35,960)	(29,555)	(333,519)	(374,402)
Provision for legal proceedings		332	67	(61,458)	(38,754)
Derivative financial instruments		—	—	(19,966)	(5,107)
Other financial liabilities		—	—	(67,643)	(53,150)
Judicial deposits		(1,644)	(1,561)	(650)	(12,589)
Post-employment benefit obligation		—	—	(10,517)	(9,848)
Other assets and liabilities, net		(13,338)	(5,646)	422,174	(152,287)
		(161,562)	(40,480)	(1,353,052)	(2,064,999)

Net cash (used in) generated from operating activities		(70,376)	45,693	2,471,109	1,729,904

Cash flows from investing activities
Capital contribution to associates	6.1	(801,558)	(331,000)	—	—
Capital reduction in subsidiaries		—	1,013,760	—	11,000
Payments for acquisition of subsidiaries		—	—	(175,032)	—
Sale (purchase) of marketable securities, net		(883,555)	193,880	(857,605)	472,358

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Interim statement of cash flows
(In thousands of Brazilian reais - R$)

		Parent Company		Consolidated
		Period of three months ended March 31,
	Note	2026	2025	2026	2025
Cash flows from operating activities
Loss before income taxes		(749,889)	(1,128,676)	(167,195)	(888,863)
Adjustments for:
Restricted cash		152	(184)	(5,594)	(114,600)
Dividends received from subsidiaries and associates		—	14,110	7,902	4,277
Dividends received from joint venture		—	5,184	—	45,640
Dividends received from finance investment		8,974	87,608	8,974	87,608
Other financial assets		—	—	(66)	(80)
Cash in the incorporation operation		—	10,089	—	—
Acquisition of property, plant and equipment, intangible and contract assets		(3,453)	(3,797)	(2,297,845)	(2,284,909)
Proceeds from the sale of investments		—	8,892,802	—	8,892,802
Related parties		—	25,592	—	25,592
Acquisition of subsidiary		—	—	—	(213,086)
Payment of derivative financial instruments, except debt		(282,637)	(981,504)	(282,637)	(981,504)
Cash received on the sale of fixed asset and intangible asset		—	—	34,787	1,024
Net cash (used in) generated from investing activities		(1,962,077)	8,926,540	(3,567,116)	5,946,122

Cash flows from financing activities
Proceeds from loans, borrowings and debentures	5.2	—	2,442,980	2,686,736	6,486,495
Principal repayment of loans, borrowings and debentures	5.2	(3,757,584)	(7,148,782)	(7,752,385)	(11,504,819)
Payment of interest on loans, borrowings and debentures	5.2	(553,805)	(459,313)	(1,627,737)	(1,271,271)
Payment of derivatives financial instruments		(565,611)	(213,110)	(1,316,126)	(938,580)
Proceeds from derivative financial instruments		3,315	347,361	28,284	979,572
Principal repayment of leases		(2,187)	(1,822)	(160,920)	(143,920)
Payment of interest on leases		(472)	(666)	(98,247)	(98,596)
Capital increase		—	—	1,058	—
Capital reduction in associates		—	—	—	(486,240)
Related parties		(2,017,479)	(1,223,068)	—	—
Payments to redeem entity’s shares and acquisition of treasury shares	10	(270,533)	(34,022)	(270,533)	(34,022)
Proceeds from the sale of treasury shares	10	31,984	—	31,984	—
Acquisition of non-controlling shareholders’ shares- Cosan Nove		—	(2,169,000)	—	(2,169,000)
Dividends paid		—	—	(90)	(44,032)
Dividends paid for preferred shares		—	—	—	(371,000)
Gain on banking operations with derivatives		—	22,100	—	22,100
Net cash (used in) generated from financing activities		(7,132,372)	(8,437,342)	(8,477,976)	(9,573,313)

(Decrease) increase in cash and cash equivalents		(9,164,825)	534,891	(9,573,983)	(1,897,287)

Cash and cash equivalents at the beginning of the period		15,383,305	2,201,267	27,243,683	16,903,542
Effect of the foreign exchange rate changes		(1,860)	(3,636)	(205,723)	(197,172)
Cash and cash equivalents at the end of the period		6,216,620	2,732,522	17,463,977	14,809,083

The accompanying notes are an integral part of the condensed interim individual and consolidated financial statements.

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Interim statement of cash flows
(In thousands of Brazilian reais - R$)

Non-cash transactions:

The Company presents its individual and consolidated Cash flows statements using the indirect method. During the three-month period ended March 31, 2026, the following transactions did not involve cash or cash equivalents and are therefore not reflected in the parent company's and consolidated Cash flows statements:

(i) Recognition of right-of-use assets as a counterpart to the lease liability, in the amount of R$ 564,946 (R$ 135,098 as of March 31, 2025), resulting from monetary adjustment based on contractual indices and the execution of new lease agreements.

(ii) Acquisition of tangible and intangible assets on a deferred payment basis, in the amount of R$ 516,674 (R$ 567,019 as of March 31, 2025).

Presentation of interest and dividends:

The Company classifies dividends and interest on equity received as Cash flows from investing activities. Dividends and interest on equity paid are classified as Cash flows from financing activities.

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Interim statement of value added

(In thousands of Brazilian reais - R$)

	Parent Company		Consolidated
	Period of three months ended March 31,
	2026	2025	2026	2025 Restated (Note 3.1)
Revenue
Net sales	—	—	10,144,646	10,641,969
Capitalization of assets constructed for own use	—	—	2,201,236	1,284,183
Other income, net	9,852	218,008	400,789	639,449
Impairment loss on trade receivables	—	—	(1,138)	(11,110)
	9,852	218,008	12,745,533	12,554,491
Inputs purchased from third parties
Cost of sales	—	—	7,004,744	6,485,994
Materials, energy, third-party services and other	42,175	39,748	827,205	724,228
Impairment	—	—	168,104	285,608
	42,175	39,748	8,000,053	7,495,830

Gross value added	(32,323)	178,260	4,745,480	5,058,661

Retention
Depreciation and amortization	5,396	4,713	971,396	967,894
Net value added	(37,719)	173,547	3,774,084	4,090,767

Value added transferred in
Interest in earnings (losses) of subsidiaries and associates	117,844	(493,236)	48,676	19,049
Interest in losses of joint ventures	(1,032)	(128,194)	(4,363)	(1,139,047)
Finance income	627,355	1,303,826	1,437,834	2,831,865
	744,167	682,396	1,482,147	1,711,867

Value added to be distributed	706,448	855,943	5,256,231	5,802,634

Distribution of value added
Personnel and payroll charges	29,394	45,508	889,975	845,288
Direct remuneration	27,274	38,243	812,706	738,191
Benefits	2,403	4,530	47,858	77,561
FGTS and other	(283)	2,735	29,411	29,536

Taxes, fees and contributions	845,685	671,267	1,704,667	2,137,093
Federal	842,660	667,807	1,147,409	1,411,485
State	—	1	510,710	683,991
Municipal	3,025	3,459	46,548	41,617

Financial expenses and rents	1,414,719	1,927,063	4,006,568	4,755,651
Interest and foreign exchange variation	1,309,096	1,827,712	3,593,618	4,367,012
Rents	4	—	42,079	25,021
Other	105,619	99,351	370,871	363,618

Equity remuneration	(1,583,350)	(1,787,895)	(1,344,979)	(1,935,398)
Proposed dividends	—	—	3,229	—
Non-controlling interests	—	—	238,371	(147,503)
Loss for the year	(1,583,350)	(1,787,895)	(1,586,579)	(1,787,895)

The accompanying notes are an integral part of the individual and consolidated financial statements.

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Notes to the condensed interim financial statement

(In thousands of Brazilian reais - R$, except when otherwise indicated)

1 Operations context

Cosan S.A. ("Cosan" or "the Company") is a publicly held Brazilian corporation listed on the Novo Mercado, the highest corporate governance tier of B3 S.A. — Brasil Bolsa Balcão ("B3"), under the trading symbol "CSAN3." The Company's American Depositary Shares (ADSs) are listed on the New York Stock Exchange (NYSE) under the ticker symbol "CSAN." Cosan is a sociedade anônima incorporated under the laws of Brazil with no fixed term and is headquartered in São Paulo, State of São Paulo. The Company's controlling shareholder is Mr. Rubens Ometto Silveira Mello.

As of March 31, 2026, the Cosan Corporate segment comprised the following entities:

Table of Contents

Notes to the condensed interim financial statement

(In thousands of Brazilian reais - R$, except when otherwise indicated)

(i)	Parent company with direct or indirect equity interest in subsidiaries and joint ventures. The main effects on its profit or loss are general and administrative expenses, contingencies, equity income and financial results attributed to loans.
(ii)	Itaú Unibanco S.A. (“Itaú”) holds preferred shares corresponding to a 12.73% stake in Cosan Nove Participações S.A. (“Cosan Nove”), which has a direct 39.06% stake in Raízen S.A. (“Raízen”).

2 Relevant events of the period

2.1 Investments

2.1.1 - Fire at the Moove lubricant factory - Compensation received

As disclosed in the financial statements ended December 31, 2025, the indirectly controlled subsidiary Cosan Lubricants e Especialidades SA ("CLE" – Moove segment) entered into a final settlement agreement with the insurance companies regarding the fire that occurred in February 2025 at the Ilha do Governador Complex, covering compensation for material damages and lost profits.

In January 2026, the insurance companies fully settled the remaining balance of the insurance indemnity (amount due under the insurance contract), in the amount of R$ 433,683, an amount already recognized as an receivable in current assets as of December 31, 2025.

2.1.2 -

Cosan S.A. 6-K