SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K Current Report Pursuant To Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): ~~November~~December 2526, 2003 INDYMAC MBS, INC. as Depositor, IndyMac Bank, F.S.B. as Seller and as Master Servicer, and Deutsche Bank National Trust Company, as trustee under the Pooling and Servicing Agreement, dated as of September 1, 2003, providing for the issuance of IndyMac MBS, Inc. Residential Asset-Securitization Trust Series 2003-A12 Mortgage Pass-Through Certificates Series 2003-L. RESIDENTIAL ASSET SECURITIZATION TRUST 2003-A12 (Exact name of Registrant as specified in its Charter) DELAWARE (State or Other Jurisdiction of Incorporation) 333-102888-10 95-4791925 (Commission File Number) (I.R.S. Employer Identification No.) 155 NORTH LAKE AVENUE PASADENA, CALIFORNIA 91101 (Address of principal executive offices) (Zip Code) Registrant's Telephone Number, Including Area Code: (800) 669-2300 Item 5. Other Events Attached hereto is a copy of the Monthly Remittance Statements to the Certificateholders which was derived from the monthly information submitted by the Master Servicer of the Trust to the Trustee. Item 7. Financial Statement and Exhibits Exhibits: (as noted in Item 5 above) Monthly Remittance Statement to the Certificateholders dated as of ~~November~~December 2526, 2003. SIGNATURE Pursuant to the requirements of the Securities Exchange Act of 1934, the Registrant has duly caused this report to be signed on its behalf by the undersigned, hereunto duly authorized. Deutsche Bank National Trust Company, not in it individual capacity, but solely as a duly authorized agent of the Registrant pursuant to the Pooling and Servicing Agreement, dated as of September 1, 2003. Date: ~~Nov~~Jan 2602, ~~2003~~2004 By: /s/ Katherine M. Wannenmacher Katherine M. Wannenmacher Vice President EXHIBIT INDEX DOCUMENT Monthly Remittance Statement to the Certificateholders dated as of ~~November~~December 2526, 2003.

	IndyMac Residential Asset Securitization Trust 2003-A12
	Mortgage Pass-Through Certificates
	November 25, 2003 Distribution
	December 26, 2003 Distribution
	Contents
			TABLE OF CONTENTS
								Page
			1.	Contents				1
			2.	Certificate Payment Report				2
			3.	Collection Account Report				4
			4.	Credit Enhancement Report				7
			5.	Collateral Report				8
			6.	Delinquency Report				11
			7.	REO Report				12
			8.	Prepayment Report				13
			9.	Prepayment Detail Report				16
			10.	Realized Loss Report				17
			11.	Realized Loss Detail Report				20
			12.	Triggers, Adj. Rate Cert. and Miscellaneous Report				21
			13.	Other Related Information				22
			14.	Additional Certificate Report				23
				Total Number of Pages				23
			CONTACTS
				Administrator: James Noriega
				Direct Phone Number: (714)247-6281
				Address: Deutsche Bank
				1761 E. St. Andrew Place, Santa Ana, CA 92705
				Web Site: https://www.corporatetrust.db.com/invr
				Factor Information: (800) 735-7777
				Main Phone Number: (714) 247-6000
ISSUANCE INFORMATION
	Seller:		IndyMac Bank					Cut-Off Date: September 1, 2003
	Certificate Insurer(s):							Closing Date: September 26, 2003
								First Payment Date: October 27, 2003
	Servicer(s):		IndyMac Bank Master Servicer
								Distribution Date: November 25, 2003
								Distribution Date: December 26, 2003
	Underwriter(s):		UBS Securities Underwriter					Record Date: ~~October~~November 3128, 2003
			Morgan Stanley Underwriter
						Page 1 of 23					© COPYRIGHT 2003 Deutsche Bank
	IndyMac Residential Asset Securitization Trust 2003-A12
	Mortgage Pass-Through Certificates
	Series 2003-A12
	Certificate Payment Report for November 25, 2003 Distribution
	Certificate Payment Report for December 26, 2003 Distribution
	Distribution in Dollars - Current Period
					Prior						Current
	Class	Original			Principal			Total	Realized	Deferred	Principal
Class	Type	Face Value			Balance	Interest	Principal	Distribution	Losses	Interest	Balance
					(1)	(2)	(3)	(4)=(2)+(3)	(5)	(6)	(7)=(1)-(3)-(5)+(6)
A-1	SEQ,AS	2,000,000.00			1,~~987~~974,~~811~~190.6183	8,~~282~~225.5580	1317,~~620~~776.7840	2126,~~903~~002.3320	-	-	1,~~974~~956,~~190~~414.8343
A-2	SEQ,AS	165,333,000.00			~~164~~163,~~325~~199,~~428~~446.5567	~~650~~645,~~454~~997.8281	1,~~125~~469,~~981~~512.8847	12,~~776~~115,~~436~~510.7028	-	-	~~163~~161,~~199~~729,~~446~~934.6720
A-3	IO,NTL	-			-	3433,~~234~~999.4688	-	3433,~~234~~999.4688	-	-	-
PO	PO,RSTP	4,866,329.00			4,~~850~~831,~~397~~115.3895	-	1921,~~281~~399.4358	1921,~~281~~399.4358	-	-	4,~~831~~809,~~115~~716.9537
A-X	IO,CSTR,NTL	-			-	30,~~335~~081.53	-	30,~~335~~081.53	-	-	-
A-R	R,AS	100.00			-	0.00	-	0.00	-	-	-
B-1	SUB,NAS	1,750,000.00			1,~~743~~737,~~694~~922.7962	7,~~265~~241.3934	56,~~772~~656.1743	13,~~037~~897.5677	-	-	1,~~737~~731,~~922~~266.6219
B-2	SUB,NAS	263,000.00			~~262~~261,~~052~~184.4295	1,~~091~~088.8927	~~867~~1,000.4737	12,~~959~~088.3664	-	-	~~261~~260,184.9558
B-3	SUB,NAS	350,000.00			~~348~~347,~~738~~584.9653	1,~~453~~448.0827	1,~~154~~331.4329	2,~~607~~779.5156	-	-	~~347~~346,~~584~~253.5324
B-4	SUB,NAS	175,000.00			~~174~~173,~~369~~792.4826	~~726~~724.5413	~~577~~665.2264	1,~~303~~389.7677	-	-	173,~~792~~126.2662
B-5	SUB,NAS	87,500.00			8786,~~184~~896.7413	~~363~~362.2707	~~288~~332.6182	~~651~~694.8889	-	-	86,~~896~~563.1331
B-6	SUB,NAS	175,070.00			~~174~~173,~~439~~861.2379	~~726~~724.8342	~~577~~665.4493	1,~~304~~390.2735	-	-	173,~~861~~195.7986
P	SUB	100.00			100.00	-	-	-	-	-	100.00
Total		175,000,099.00			~~173~~172,~~954~~786,~~217~~095.1673	~~734~~729,~~934~~893.3652	1,~~168~~519,~~121~~340.4393	12,~~903~~249,~~055~~234.7945	-	-	~~172~~171,~~786~~266,~~095~~754.7380
Interest payments to Class PO represent payments of the Class PO Deferred Amount
	Interest Accrual Detail				Current Period Factor Information per $1,000 of Original Face
						Orig. Principal	Prior				Current
	Period	Period				(with Notional)	Principal			Total	Principal
Class	Starting	Ending		Method	Cusip	Balance	Balance	Interest	Principal	Distribution	Balance
							(1)	(2)	(3)	(4)=(2)+(3)	(5)
A-1				F-30/360	45660NVM4	2,000,000.00	~~993~~987.~~905805~~095415	4.~~141275~~112900	68.~~810390~~888200	1013.~~951665~~001100	~~987~~978.~~095415~~207215
A-2				F-30/360	45660NVN2	165,333,000.00	~~993~~987.~~905806~~095418	3.~~934210~~907253	68.~~810388~~888198	1012.~~744598~~795451	~~987~~978.~~095418~~207219
A-3				F-30/360	45660NVP7	8,266,650.00	~~993~~987.~~905806~~095418	4.~~141274~~112897	-	4.~~141274~~112897	~~987~~978.~~095418~~207219
PO				-	45660NVQ5	4,866,329.00	~~996~~992.~~726152~~763940	-	34.~~962213~~397479	34.~~962213~~397479	~~992~~988.~~763940~~366461
A-X				A-30/360	45660NVR3	92,090,325.00	~~991~~992.~~581923~~598944	0.~~329411~~326652	-	0.~~329411~~326652	~~982~~979.~~481856~~855362
A-R				F-30/360	45660NVS1	100.00	-	0.~~039000~~007000	-	0.~~039000~~007000	-
B-1				F-30/360	45660NVT9	1,750,000.00	~~996~~993.~~397023~~098642	4.~~151651~~137909	3.~~298381~~803675	7.~~450032~~941584	~~993~~989.~~098642~~294967
B-2				F-30/360	45660NVU6	263,000.00	~~996~~993.~~397034~~098654	4.~~151673~~137909	3.~~298381~~803675	7.~~450054~~941584	~~993~~989.~~098654~~294978
B-3				F-30/360	45660NVV4	350,000.00	~~996~~993.~~397029~~098648	4.~~151657~~137914	3.~~298381~~803675	7.~~450038~~941590	~~993~~989.~~098648~~294972
B-4				F-30/360	45660NVW2	175,000.00	~~996~~993.~~397029~~098648	4.~~151657~~137886	3.~~298381~~803675	7.~~450038~~941561	~~993~~989.~~098648~~294973
B-5				F-30/360	45660NVX0	87,500.00	~~996~~993.~~397029~~098648	4.~~151657~~137943	3.~~298381~~803675	7.~~450038~~941618	~~993~~989.~~098648~~294973
B-6				F-30/360	45660NVY8	175,070.00	~~996~~993.~~397041~~098718	4.~~151654~~137888	3.~~298324~~803790	7.~~449977~~941678	~~993~~989.~~098718~~294928
P				-		100.00	1,000.000000	-	-	-	1,000.000000
							Page 2 of 23				© COPYRIGHT 2003 Deutsche Bank
	IndyMac Residential Asset Securitization Trust 2003-A12
	Mortgage Pass-Through Certificates
	Series 2003-A12
	Certificate Payment Report for November 25, 2003 Distribution
	Certificate Payment Report for December 26, 2003 Distribution
	Distribution in Dollars - to Date
											Current
	Original				Unscheduled	Scheduled	Total	Total	Realized	Deferred	Principal
Class	Face Value		Interest		Principal	Principal	Principal	Distribution	Losses	Interest	Balance
	(1)		(2)		(3)	(4)	(5)=(3)+(4)	(6)=(2)+(5)	(7)	(8)	(9)=(1)-(5)-(7)+(8)
A-1	2,000,000.00		1624,~~615~~841.8868		1222,~~527~~670.6605	1320,~~281~~915.5152	2543,~~809~~585.1757	4268,~~425~~427.0525	-	-	1,~~974~~956,~~190~~414.8343
A-2	165,333,000.00		1,~~304~~950,~~897~~895.9576		1,~~035~~874,~~617~~053.9571	1,~~097~~729,~~935~~012.3809	23,~~133~~603,~~553~~065.3380	35,~~438~~553,~~451~~961.2856	-	-	~~163~~161,~~199~~729,~~446~~934.6720
A-3	-		68102,678.8472		-	-	-	68102,678.8472	-	-	-
PO	4,866,329.00		-		35,~~008~~735.2818	3250,~~204~~877.7745	3556,~~213~~612.0563	3556,~~213~~612.0563	-	-	4,~~831~~809,~~115~~716.9537
A-X	-		6191,~~476~~558.6417		-	-	-	6191,~~476~~558.6417	-	-	-
A-R	100.00		0.42		45.48	54.52	100.00	100.42	-	-	-
B-1	1,750,000.00		1421,~~557~~798.0640		59,~~827~~625.4733	69,~~249~~108.9048	1218,~~077~~733.3881	2640,~~634~~532.4421	-	-	1,~~737~~731,~~922~~266.6219
B-2	263,000.00		23,~~187~~275.7299		~~875~~1,446.7955	~~939~~1,368.2788	12,815.0642	46,~~002~~091.7841	-	-	~~261~~260,184.9558
B-3	350,000.00		24,~~911~~359.4168		1,~~165~~925.4907	1,~~249~~821.9870	23,~~415~~746.4876	58,~~326~~106.8944	-	-	~~347~~346,~~584~~253.5324
B-4	175,000.00		12,~~455~~179.7184		~~582~~962.7553	~~624~~910.9985	1,~~207~~873.7438	24,~~663~~053.4522	-	-	173,~~792~~126.2662
B-5	87,500.00		~~727~~1,089.8592		~~291~~481.3727	~~312~~455.5042	~~603~~936.8769	12,~~331~~026.7261	-	-	86,~~896~~563.1331
B-6	175,070.00		12,~~456~~180.2971		~~582~~962.9892	~~625~~911.2422	1,~~208~~874.2114	24,~~664~~054.5085	-	-	173,~~861~~195.7986
P	100.00		-		-	-	-	-	-	-	100.00
Total	175,000,099.00		12,~~474~~204,~~965~~859.7729		1,~~060~~917,~~525~~908.2309	1,~~153~~815,~~478~~436.0512	23,~~214~~733,~~003~~344.2821	35,~~688~~938,~~969~~203.0550	-	-	~~172~~171,~~786~~266,~~095~~754.7380
	Interest Detail
	Pass-	Prior Principal				Non-	Prior	Unscheduled		Paid or	Current
	Through	(with Notional)			Accrued	Supported	Unpaid	Interest	Optimal	Deferred	Unpaid
Class	Rate	Balance			Interest	Interest SF	Interest	Adjustments	Interest	Interest	Interest
					(1)	(2)	(3)	(4)	(5)=(1)-(2)+(3)+(4)	(6)	(7)=(5)-(6)
A-1	5.00000%	1,~~987~~974,~~811~~190.6183			8,~~282~~225.5580	-	-	-	8,~~282~~225.5580	8,~~282~~225.5580	-
A-2	4.75000%	~~164~~163,~~325~~199,~~428~~446.5567			~~650~~645,~~454~~997.8281	-	-	-	~~650~~645,~~454~~997.8281	~~650~~645,~~454~~997.8281	-
A-3	5.00000%	8,~~216~~159,~~271~~972.4333			3433,~~234~~999.4688	-	-	-	3433,~~234~~999.4688	3433,~~234~~999.4688	-
PO		4,~~850~~831,~~397~~115.3895			-	-	-	-	-	-	-
A-X	0.~~39865~~39491%	91,~~315~~408,~~101~~759.6038			30,~~335~~081.53	-	-	-	30,~~335~~081.53	30,~~335~~081.53	-
A-R	5.00000%	-			-	-	~~0.00~~-	-	~~0.00~~-	0.00	-
B-1	5.00000%	1,~~743~~737,~~694~~922.7962			7,~~265~~241.3934	-	-	-	7,~~265~~241.3934	7,~~265~~241.3934	-
B-2	5.00000%	~~262~~261,~~052~~184.4295			1,~~091~~088.8927	-	-	-	1,~~091~~088.8927	1,~~091~~088.8927	-
B-3	5.00000%	~~348~~347,~~738~~584.9653			1,~~453~~448.0827	-	-	-	1,~~453~~448.0827	1,~~453~~448.0827	-
B-4	5.00000%	~~174~~173,~~369~~792.4826			~~726~~724.5413	-	-	-	~~726~~724.5413	~~726~~724.5413	-
B-5	5.00000%	8786,~~184~~896.7413			~~363~~362.2707	-	-	-	~~363~~362.2707	~~363~~362.2707	-
B-6	5.00000%	~~174~~173,~~439~~861.2379			~~726~~724.8342	-	-	-	~~726~~724.8342	~~726~~724.8342	-
P		100.00			-	-	-	-	-	-	-
Total		~~273~~272,~~485~~354,~~590~~827.1845			~~734~~729,~~934~~893.3652	-	~~0.00~~-	-	~~734~~729,~~934~~893.3652	~~734~~729,~~934~~893.3652	-
							Page 3 of 23				© COPYRIGHT 2003 Deutsche Bank
	IndyMac Residential Asset Securitization Trust 2003-A12
	Mortgage Pass-Through Certificates
	Collection Account Report for November 25, 2003 Distribution
	Collection Account Report for December 26, 2003 Distribution
	Collection Account Report
SUMMARY								TOTAL
	Principal Collections							1,~~166~~519,~~247~~340.3491
	Principal Withdrawals							0.00
	Principal Other Accounts							~~1,874~~0.0900
	TOTAL PRINCIPAL							1,~~168~~519,~~121~~340.4391
	Interest Collections							~~649~~773,~~591~~227.3638
	Interest Withdrawals							(1143,~~396~~333.1484)
	Interest Other Accounts							~~96,739~~0.1400
	TOTAL INTEREST							~~734~~729,~~934~~893.3654
	TOTAL AVAILABLE FUNDS TO BONDHOLDERS							12,~~903~~249,~~055~~234.7945
	Interest Payable to Bondholders							~~734~~729,~~934~~893.3654
	Principal Payment Amount Payable to Bondholders							1,~~168~~519,~~121~~340.4391
PRINCIPAL - COLLECTIONS								TOTAL
	Scheduled Principal							~~575~~661,~~920~~958.0107
	Curtailments							90100,~~327~~302.3387
	Prepayments in Full							~~500~~757,~~000~~079.0097
	Repurchases/Substitutions							0.00
	Liquidations							0.00
	Insurance Principal							0.00
	Other Additional Principal							0.00
	LESS: Delinquent Principal							(~~428~~2,~~392~~220.7412)
	LESS: Realized Losses							0.00
	PLUS: Recoveries							0.00
	PLUS: Substitution Shortfall Principal							0.00
	PLUS: Principal Loan Adjustments							0.00
	PLUS: Principal Advanced							~~428~~2,~~392~~220.7412
	TOTAL PRINCIPAL							1,~~166~~519,~~247~~340.3491
				Page 4 of 23				© COPYRIGHT 2003 Deutsche Bank
	IndyMac Residential Asset Securitization Trust 2003-A12
	Mortgage Pass-Through Certificates
	Collection Account Report for November 25, 2003 Distribution
	Collection Account Report for December 26, 2003 Distribution
	Collection Account Report
PRINCIPAL - WITHDRAWALS								TOTAL
SPACE INTENTIONALLY LEFT BLANK
PRINCIPAL - OTHER ACCOUNTS								TOTAL
	Pre-Funding Release Amount							~~1,874~~0.0900
	TOTAL PRINCIPAL OTHER ACCOUNTS							~~1,874~~0.0900
INTEREST - COLLECTIONS								TOTAL
	Scheduled Interest							~~676~~773,~~447~~349.0507
	Repurchases/Substitutions							0.00
	Liquidations							0.00
	Insurance Interest							0.00
	Other Additional Interest							0.00
	LESS: Prepayment Interest Shortfalls							~~(1,508~~0.~~33)~~00
	LESS: Delinquent Interest							(~~504~~2,~~109~~433.3370)
	LESS: Interest Realized Losses							0.00
	PLUS: Compensating Interest							~~1,508~~0.3300
	LESS: Civil Relief Act Shorfalls							0.00
	PLUS: Substiution Shortfall Interest							0.00
	PLUS: Interest Loan Adjustments							0.00
	LESS: Excess, Special Hazard, Fraud, & Bankruptcy Interest Losses							0.00
	Interest Advanced							~~477~~2,~~253~~312.6401
	TOTAL INTEREST							~~649~~773,~~591~~227.3638
				Page 5 of 23				© COPYRIGHT 2003 Deutsche Bank
	IndyMac Residential Asset Securitization Trust 2003-A12
	Mortgage Pass-Through Certificates
	Collection Account Report for November 25, 2003 Distribution
	Collection Account Report for December 26, 2003 Distribution
	Collection Account Report
INTEREST - WITHDRAWALS								TOTAL
SPACE INTENTIONALLY LEFT BLANK
INTEREST - OTHER ACCOUNTS								TOTAL
	Prepayment Penalties							0.00
	Capitalized Interest							~~96,739~~0.1400
	TOTAL INTEREST OTHER ACCOUNTS							~~96,739~~0.1400
INTEREST - FEES								TOTAL
	Current Servicing Fees							941,~~221~~174.7102
	Trustee Fees							2,~~174~~159.4382
	TOTAL INTEREST FEES							1143,~~396~~333.1484
				Page 6 of 23				© COPYRIGHT 2003 Deutsche Bank
	IndyMac Residential Asset Securitization Trust 2003-A12
	Mortgage Pass-Through Certificates
	Credit Enhancement Report for November 25, 2003 Distribution
	Credit Enhancement Report for December 26, 2003 Distribution
	Credit Enhancement Report
ACCOUNTS								TOTAL
SPACE INTENTIONALLY LEFT BLANK
INSURANCE								TOTAL
SPACE INTENTIONALLY LEFT BLANK
STRUCTURAL FEATURES								TOTAL
SPACE INTENTIONALLY LEFT BLANK
				Page 7 of 23				© COPYRIGHT 2003 Deutsche Bank
	IndyMac Residential Asset Securitization Trust 2003-A12
	Mortgage Pass-Through Certificates
	Collateral Report for November 25, 2003 Distribution
	Collateral Report for December 26, 2003 Distribution
	Collateral Report
COLLATERAL								TOTAL
	Loan Count:
	Original							398
	Prior							~~396~~395
	Prefunding							-53
	Scheduled Paid Offs							-
	Full Voluntary Prepayments							(12)
	Repurchases							-
	Liquidations							-
	Current							~~395~~446
	Principal Balance:
	Original							152,173,984.73
	Prior							~~151~~149,~~128~~961,~~102~~855.8854
	Prefunding							-22,824,141.18
	Scheduled Principal							(~~575~~661,~~920~~958.0107)
	Partial and Full Voluntary Prepayments							(~~590~~857,~~327~~382.3384)
	Repurchases							-
	Liquidations							-
	Current							~~149~~171,~~961~~266,~~855~~655.5481
PREFUNDING								TOTAL
SPACE INTENTIONALLY LEFT BLANK
Current Prin Balance by Groups (in millions of dollars)					Total Current Principal Balance (in millions of dollars)
				Page 8 of 23				© COPYRIGHT 2003 Deutsche Bank
	IndyMac Residential Asset Securitization Trust 2003-A12
	Mortgage Pass-Through Certificates
	Collateral Report for November 25, 2003 Distribution
	Collateral Report for December 26, 2003 Distribution
	Collateral Report
CHARACTERISTICS								TOTAL
	Weighted Average Coupon Original							5.376073%
	Weighted Average Coupon Prior							5.~~376073~~371181%
	Weighted Average Coupon Current							5.~~371181~~370915%
	Weighted Average Months to Maturity Original							174
	Weighted Average Months to Maturity Prior							~~174~~173
	Weighted Average Months to Maturity Current							173
	Weighted Avg Remaining Amortization Term Original							174
	Weighted Avg Remaining Amortization Term Prior							~~174~~173
	Weighted Avg Remaining Amortization Term Current							~~173~~172
	Weighted Average Seasoning Original							5.57
	Weighted Average Seasoning Prior							56.5759
	Weighted Average Seasoning Current							67.5919
Note: Original information refers to deal issue.
WAC by Groups					Total WAC
WARAT by Groups					Total WARAT
Note: Dates correspond to distribution dates.
				Page 9 of 23				© COPYRIGHT 2003 Deutsche Bank
	IndyMac Residential Asset Securitization Trust 2003-A12
	Mortgage Pass-Through Certificates
	Collateral Report for November 25, 2003 Distribution
	Collateral Report for December 26, 2003 Distribution
	Collateral Report
ARM CHARACTERISTICS								TOTAL
	Weighted Average Margin Original							0.000%
	Weighted Average Margin Prior							0.000%
	Weighted Average Margin Current							0.000%
	Weighted Average Max Rate Original							0.000%
	Weighted Average Max Rate Prior							0.000%
	Weighted Average Max Rate Current							0.000%
	Weighted Average Min Rate Original							0.000%
	Weighted Average Min Rate Prior							0.000%
	Weighted Average Min Rate Current							0.000%
	Weighted Average Cap Up Original							0.000%
	Weighted Average Cap Up Prior							0.000%
	Weighted Average Cap Up Current							0.000%
	Weighted Average Cap Down Original							0.000%
	Weighted Average Cap Down Prior							0.000%
	Weighted Average Cap Down Current							0.000%
Note: Original information refers to deal issue.
SERVICING FEES / ADVANCES								TOTAL
	Current Servicing Fees							941,~~221~~174.7102
	Delinquent Servicing Fees							~~26,855~~121.6968
	TOTAL SERVICING FEES							3641,~~077~~295.4070
	Total Servicing Fees							3641,~~077~~295.4070
	Compensating Interest							~~(1,508~~0.~~33)~~00
	Delinquent Servicing Fees							(~~26,855~~121.6968)
	COLLECTED SERVICING FEES							741,~~713~~174.3802
	Total Advanced Principal For Current Payment Date							~~428~~2,~~392~~220.7412
	Total Advanced Interest For Current Payment Date							~~477~~2,~~253~~312.6401
	TOTAL ADVANCES FOR CURRENT PERIOD							~~905~~4,~~646~~532.3813
ADDITIONAL COLLATERAL INFORMATION								TOTAL
	Prepayment Interest Shortfall (PPIS)							~~1,508~~0.3300
	Compensating Interest							~~(1,508~~0.~~33)~~00
	Net Prepayment Interest Shortfall (Net PPIS)							0.00
	Weighted Average Net Mortgage Rate							5.~~069717~~069116%
				Page 10 of 23				© COPYRIGHT 2003 Deutsche Bank
	IndyMac Residential Asset Securitization Trust 2003-A12
	Mortgage Pass-Through Certificates
	Delinquency Report for November 25, 2003 Distribution
	Delinquency Report for December 26, 2003 Distribution
	Delinquency Report - Total
				<1 PAYMENT	1 PAYMENT	2 PAYMENTS	3+ PAYMENTS	TOTAL
DELINQUENT		Balance		~~###########~~-	-581,867.23	-	-	-581,867.23
		% Balance		740.8500%	0.0034%	0.00%	0.00%	0.0034%
		# Loans		~~295~~-	-1	-	-	-1
		% # Loans		740.6800%	0.0022%	0.00%	0.00%	0.0022%
FORECLOSURE		Balance		-	-	-	-	-
		% Balance		0.00%	0.00%	0.00%	0.00%	0.00%
		# Loans		-	-	-	-	-
		% # Loans		0.00%	0.00%	0.00%	0.00%	0.00%
BANKRUPTCY		Balance		-	-	-	-	-
		% Balance		0.00%	0.00%	0.00%	0.00%	0.00%
		# Loans		-	-	-	-	-
		% # Loans		0.00%	0.00%	0.00%	0.00%	0.00%
REO		Balance		-	-	-	-	-
		% Balance		0.00%	0.00%	0.00%	0.00%	0.00%
		# Loans		-	-	-	-	-
		% # Loans		0.00%	0.00%	0.00%	0.00%	0.00%
TOTAL		Balance		-	-581,867.23	-	-	-581,867.23
		% Balance		0.00%	0.0034%	0.00%	0.00%	0.0034%
		# Loans		-	-1	-	-	-1
		% # Loans		0.00%	0.0022%	0.00%	0.00%	0.0022%
Note: <1 Payment = 1-30days, 1 Payment = 31-60days, 2 Payments = 61-90days, 3+ Payments = 91+
								6 Months Moving Average
1 or 2 Payments Delinquent					3 or More Payments Delinquent
Total Foreclosure					Total Bankruptcy and REO
Note: Dates correspond to distribution dates.
				Page 11 of 23				© COPYRIGHT 2003 Deutsche Bank
	IndyMac Residential Asset Securitization Trust 2003-A12
	Mortgage Pass-Through Certificates
	REO Report for November 25, 2003 Distribution
	REO Report for December 26, 2003 Distribution
	REO Report - Mortgage Loans that Become REO During Current Distribution
SUMMARY				LOAN GROUP
Total Loan Count = 0				Loan Group 1 = Group; REO Book Value = 000.00
Total Original Principal Balance = 000.00
Total Current Balance = 000.00
REO Book Value = 000.00
REO Book Value reported corresponds to total REO loans, including loans that become REO during current distribution.
Loan Number		Original	Stated		Current	State &
&		Principal	Principal	Paid to	Note	LTV at	Original	Origination
Loan Group		Balance	Balance	Date	Rate	Origination	Term	Date
SPACE INTENTIONALLY LEFT BLANK
				Page 12 of 23				© COPYRIGHT 2003 Deutsche Bank
	IndyMac Residential Asset Securitization Trust 2003-A12
	Mortgage Pass-Through Certificates
	Prepayment Report for November 25, 2003 Distribution
	Prepayment Report for December 26, 2003 Distribution
	Prepayment Report - Voluntary Prepayments
VOLUNTARY PREPAYMENTS								TOTAL
	Current
	Number of Paid in Full Loans							12
	Number of Repurchased Loans							-
	Total Number of Loans Prepaid in Full							12
	Paid in Full Balance							~~500~~757,~~000~~079.0097
	Repurchased Loans Balance							-
	Curtailments Amount							90100,~~327~~302.3387
	Total Prepayment Amount							~~590~~857,~~327~~382.3384
	Cumulative
	Number of Paid in Full Loans							24
	Number of Repurchased Loans							1
	Total Number of Loans Prepaid in Full							35
	Paid in Full Balance							~~940~~1,~~268~~697,348.2724
	Repurchased Loans Balance							51,500.00
	Curtailments Amount							66167,~~882~~185.8774
	Total Prepayment Amount							1,~~058~~916,~~651~~033.1498
SPACE INTENTIONALLY LEFT BLANK
Total Prepayments by Groups (in thousands of dollars)					Total Prepayments (in thousands of dollars)
				Page 13 of 23				© COPYRIGHT 2003 Deutsche Bank
	IndyMac Residential Asset Securitization Trust 2003-A12
	Mortgage Pass-Through Certificates
	Prepayment Report for November 25, 2003 Distribution
	Prepayment Report for December 26, 2003 Distribution
	Prepayment Report - Voluntary Prepayments
VOLUNTARY PREPAYMENT RATES								TOTAL
	SMM							0.3950%
	3 Months Avg SMM							0.40%
	12 Months Avg SMM
	Avg SMM Since Cut-off							0.3540%
	CPR							45.6182%
	3 Months Avg CPR							4.69%
	12 Months Avg CPR
	Avg CPR Since Cut-off							4.1369%
	PSA							~~349~~404.4050%
	3 Months Avg PSA Approximation							363.71%
	12 Months Avg PSA Approximation
	Avg PSA Since Cut-off Approximation							~~339~~363.1971%
CPR by Groups					Total CPR
PSA by Groups					Total PSA
				Page 14 of 23				© COPYRIGHT 2003 Deutsche Bank
	IndyMac Residential Asset Securitization Trust 2003-A12
	Mortgage Pass-Through Certificates
	Prepayment Report for November 25, 2003 Distribution
	Prepayment Report for December 26, 2003 Distribution
	Prepayment Report - Voluntary Prepayments
CPR Avg since Cut-Off by Groups					Total CPR Avg since Cut-Off
PSA Avg since Cut-Off by Groups					Total PSA Avg since Cut-Off
PREPAYMENT CALCULATION METHODOLOGY
Single Monthly Mortality (SMM): (Voluntary partial and full prepayments + Repurchases)/(Beg Principal Balance - Sched Principal)
Conditional Prepayment Rate (CPR): 1-((1-SMM)^12)
PSA Standard Prepayment Model: CPR/(0.02*min(30,WAS))
Average SMM over period between nth month and mth month (AvgSMMn,m): [(1-SMMn) * (1-SMMn+1) .......(1-SMMm)]^(1/months in period n,m)
Average CPR over period between the nth month and mth month (AvgCPRn,m): 1-((1-AvgSMMn,m)^12)
Average PSA Approximation over period between the nth month and mth month: AvgCPRn,m/(0.02*Avg WASn,m))
Average WASn,m: (min(30,WASn)+min(30,WASn+1)+.......+min(30,WASm)/(number of months in the period n,m)
Weighted Average Seasoning (WAS)
Note: Prepayment rates are calculated since deal issue date and include partial and full voluntary prepayments and repurchases.
Dates correspond to distribution dates.
				Page 15 of 23				© COPYRIGHT 2003 Deutsche Bank
	IndyMac Residential Asset Securitization Trust 2003-A12
	Mortgage Pass-Through Certificates
	Prepayment Detail Report for November 25, 2003 Distribution
	Prepayment Detail Report for December 26, 2003 Distribution
	Prepayment Detail Report - Loans Prepaid in Full During Current Distribution
SUMMARY						LOAN GROUP
Total Loan Count = 1						Loan Group 1 = Group
Total Loan Count = 2						Loan Group 1 = Group
Total Original Principal Balance = 500,000.00
Total Original Principal Balance = 792,000.00
Total Prepayment Amount = 500,000.00
Total Prepayment Amount = 757,079.97
Loan Number			Original			Current	State &	Type Prepayment
&		Loan	Principal	Prepayment	Prepayment	Note	LTV at	&	Origination
Loan Group		Status	Balance	Amount	Date	Rate	Origination	Original Term	Date
2876305 1			500,000.00	500,000.00	Oct-11-03	5.750%	CA - 68.63%	Paid Off - 180	Sep-09-03
1361538 1			432,000.00	399,433.01	Nov-21-03	5.875%	NY - 70.70%	Paid Off - 180	Dec-27-01
2698965 1			360,000.00	357,646.96	Dec-12-03	6.625%	NY - 80.00%	Paid Off - 180	Aug-06-03
					Page 16 of 23				© COPYRIGHT 2003 Deutsche Bank
	IndyMac Residential Asset Securitization Trust 2003-A12
	Mortgage Pass-Through Certificates
	Realized Loss Report for November 25, 2003 Distribution
	Realized Loss Report for December 26, 2003 Distribution
	Realized Loss Report - Collateral
COLLATERAL REALIZED LOSSES								TOTAL
	Current
	Number of Loans Liquidated							-
	Collateral Realized Loss/(Gain) Amount							-
	Net Liquidation Proceeds							-
	Cumulative
	Number of Loans Liquidated							-
	Collateral Realized Loss/(Gain) Amount							-
	Net Liquidation Proceeds							-
	Note: Collateral Realized Loss Amount may include adjustments to loans liquidated in prior periods.
	Current Realized Losses							0.00
	Supplemental Losses (Recoveries)							0.00
	Current Net Realized Losses (Recoveries)							0.00
	Prior Cumulative Realized Loss							0.00
	Current Net Realized Loss (Recoveries)							0.00
	Current Cumulative Realized Loss							0.00
	Current Special Hazard Loss Coverage Amount							3,~~665~~650,~~440~~663.1357
	Current Fraud Loss Coverage Amount							1,750,000.00
	Current Bankruptcy Loss Coverage Amount							100,000.00
	Class B-1 Write Down Amount							0.00
	Class B-2 Write Down Amount							0.00
	Class B-3 Write Down Amount							0.00
	Class B-4 Write Down Amount							0.00
	Class B-5 Write Down Amount							0.00
	Class B-6 Write Down Amount							0.00
							3 Months Moving Average
Collateral Loss Severity Approximation by Groups					Collateral Loss Severity Approximation
				Page 17 of 23				© COPYRIGHT 2003 Deutsche Bank
	IndyMac Residential Asset Securitization Trust 2003-A12
	Mortgage Pass-Through Certificates
	Realized Loss Report for November 25, 2003 Distribution
	Realized Loss Report for December 26, 2003 Distribution
	Realized Loss Report - Collateral
DEFAULT SPEEDS								TOTAL
	MDR							0.00%
	3 Months Avg MDR							0.00%
	12 Months Avg MDR
	Avg MDR Since Cut-off							0.00%
	CDR							0.00%
	3 Months Avg CDR							0.00%
	12 Months Avg CDR
	Avg CDR Since Cut-off							0.00%
	SDA							0.00%
	3 Months Avg SDA Approximation							0.00%
	12 Months Avg SDA Approximation
	Avg SDA Since Cut-off Approximation							0.00%
	Loss Severity Approximation for Current Period
	3 Months Avg Loss Severity Approximation
	12 Months Avg Loss Severity Approximation
	Avg Loss Severity Approximation Since Cut-off
CDR by Groups					Total CDR
SDA by Groups					Total SDA
				Page 18 of 23				© COPYRIGHT 2003 Deutsche Bank
	IndyMac Residential Asset Securitization Trust 2003-A12
	Mortgage Pass-Through Certificates
	Realized Loss Report for November 25, 2003 Distribution
	Realized Loss Report for December 26, 2003 Distribution
	Realized Loss Report - Collateral
CDR Avg since Cut-Off by Groups					Total CDR Avg since Cut-Off
SDA Avg since Cut-Off by Groups					Total SDA Avg since Cut-Off
COLLATERAL REALIZED LOSS CALCULATION METHODOLOGY
Monthly Default Rate (MDR): (Beg Principal Balance of Liquidated Loans)/(Total Beg Principal Balance)
Conditional Default Rate (CDR): 1-((1-MDR)^12)
SDA Standard Default Assumption: CDR/IF(WAS<61,MIN(30,WAS)0.02,MAX(0.03,MIN(30,WAS)0.02-0.0095*(WAS-60)))
Average MDR over period between nth month and mth month (AvgMDRn,m): [(1-MDRn) * (1-MDRn+1) .......(1-MDRm)]^(1/months in period n,m)
Average CDR over period between the nth month and mth month (AvgCDRn,m): 1-((1-AvgMDRn,m)^12)
Average SDA Approximation over period between the nth month and mth month:
AvgCDRn,m/IF(Avg WASn,m<61,MIN(30,Avg WASn,m)0.02,MAX(0.03,MIN(30,Avg WASn,m)0.02-0.0095*(Avg WASn,m-60)))
Average WASn,m: (WASn + WASn+1 +.......+ WASm )/(number of months in the period n,m)
Loss Severity Approximation for current period: sum(Realized Loss Amount)/sum(Beg Principal Balance of Liquidated Loans)
Average Loss Severity Approximation over period between nth month and mth month: Avg(Loss Severityn,m)
Note: Default rates are calculated since deal issue date and include realized gains and additional realized losses and gains from prior periods.
Dates correspond to distribution dates.
				Page 19 of 23				© COPYRIGHT 2003 Deutsche Bank
	IndyMac Residential Asset Securitization Trust 2003-A12
	Mortgage Pass-Through Certificates
	Realized Loss Detail Report for November 25, 2003 Distribution
	Realized Loss Detail Report for December 26, 2003 Distribution
	Realized Loss Detail Report - Loans Liquidated During Current Distribution
SUMMARY						LOAN GROUP
Total Loan Count = 0						Loan Group 1 = Group
Total Original Principal Balance = 0.00
Total Prior Principal Balance = 0.00
Total Realized Loss Amount = 0.00
Total Net Liquidation Proceeds = 0.00
Note: Total Realized Loss Amount may include adjustments to loans liquidated in prior periods.
Loan Number			Original	Prior		Current	State &
&		Loan	Principal	Principal	Realized	Note	LTV at	Original	Origination
Loan Group		Status	Balance	Balance	Loss/(Gain)	Rate	Origination	Term	Date
SPACE INTENTIONALLY LEFT BLANK
					Page 20 of 23				© COPYRIGHT 2003 Deutsche Bank
	IndyMac Residential Asset Securitization Trust 2003-A12
	Mortgage Pass-Through Certificates
	Triggers, Adj. Rate Cert. and Miscellaneous Report for November 25, 2003 Distribution
	Triggers, Adj. Rate Cert. and Miscellaneous Report for December 26, 2003 Distribution
	Triggers, Adj. Rate Cert. and Miscellaneous Report
TRIGGER EVENTS								TOTAL
	Has the Optional Termination Date been reached?							No
	Have the Sr. Prepay Step Down Cond been satisfied?							No
	Has the Sr. Credit Supp. Depletion Date been reached?							No
	Has the Spec. Haz. Coverage Term Date been reached?							No
	Has the Fraud LossCoverage Term. Date been reached?							No
	Has the Bank LossCoverage Term. Date been reached?							No
ADJUSTABLE RATE CERTIFICATE INFORMATION								TOTAL
SPACE INTENTIONALLY LEFT BLANK
ADDITIONAL INFORMATION								TOTAL
	Current Senior Percentage							98.~~349841~~344054%
	Next Senior Percentage							98.~~344054~~335552%
	Current Subordinate Percentage							1.~~650159~~655946%
	Next Subordinate Percentage							1.~~655946~~664448%
	Current Senior Prepayment Percentage							100.000000%
	Next Projected Senior Prepayment Percentage							100.000000%
	Current Subordinated Prepayment Percentage							0.000000%
	Next Projected Subordinated Prepayment Percentage							0.000000%
	Next Projected Pass-Through Rate for Class A-2							4.750000%
	Next Projected Pass-Through Rate for Class A-X							0.~~398590~~390756%
	Next Projected Pass-Through Rate for all other classes							5.000000%
				Page 21 of 23				© COPYRIGHT 2003 Deutsche Bank
	IndyMac Residential Asset Securitization Trust 2003-A12
	Mortgage Pass-Through Certificates
	Other Related Information for November 25, 2003 Distribution
	Other Related Information for December 26, 2003 Distribution
	Other Related Information
ADDITIONAL INFORMATION								TOTAL
	Scheduled Principal
	1 Month Prior							~~575~~661,~~920~~958.0107
	2 Months Prior							~~577~~575,~~558~~920.0401
	3 Months Prior							0577,558.0004
	4 Months Prior							0.00
	5 Months Prior							0.00
	6 Months Prior							0.00
	7 Months Prior							0.00
	8 Months Prior							0.00
	9 Months Prior							0.00
	10 Months Prior							0.00
	11 Months Prior							0.00
	12 Months Prior							0.00
	Scheduled Principal on 60+ Day Delinquent Loans
	1 Month Prior							0.00
	2 Months Prior							0.00
	3 Months Prior							0.00
	4 Months Prior							0.00
	5 Months Prior							0.00
	6 Months Prior							0.00
	7 Months Prior							0.00
	8 Months Prior							0.00
	9 Months Prior							0.00
	10 Months Prior							0.00
	11 Months Prior							0.00
	12 Months Prior							0.00
				Page 22 of 23				© COPYRIGHT 2003 Deutsche Bank
	IndyMac Residential Asset Securitization Trust 2003-A12
	Mortgage Pass-Through Certificates
	Additional Certificate Report for November 25, 2003 Distribution
	Additional Certificate Report for December 26, 2003 Distribution
	Additional Certificate Report
	CLASS				Net PPIS & Relief Act Shortfall Allocation	Unpaid Interest Amount Due	Unpaid Interest Paid	Remaining Unpaid Interest Amount
	A-1				0.00	0.00	0.00	0.00
	A-2				0.00	0.00	0.00	0.00
	A-3				0.00	0.00	0.00	0.00
	PO				0.00	0.00	0.00	0.00
	A-X				0.00	0.00	0.00	0.00
	A-R				0.00	0.00	0.00	0.00
	B-1				0.00	0.00	0.00	0.00
	B-2				0.00	0.00	0.00	0.00
	B-3				0.00	0.00	0.00	0.00
	B-4				0.00	0.00	0.00	0.00
	B-5				0.00	0.00	0.00	0.00
	B-6				0.00	0.00	0.00	0.00
				Page 23 of 23				© COPYRIGHT 2003 Deutsche Bank

Filing Compare · RESIDENTIAL ASSET SECURITIZATION TRUST 2003-A12