
                                       UNITED STATES
                           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):  December 27, 2004
                          (Date of earliest event reported)

            Indymac MBS Inc (as Depositor under the Pooling and Servicing
                Agreement, dated as November 1, 2004, providing for the
               issuance of IndyMac INDX Mortgage Loan Trust 2004-AR12
                Mortgage Pass-Through Certificates, Series 2004-AR12)
                 (Exact name of registrant as specified in charter)


                                         DELAWARE
                     (State or Other Jurisdiction of Incorporation)

               333-119384-02                         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

       (Former name or former address, if changed since last report.)

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any
of the following provisions (see General Instruction A.2. below):

[  ] Written communications pursuant to Rule 425 under the Securities Act
(17 CFR 230.425)

[  ] Soliciting material pursuant to Rule 14a-12(b) under the Exchange Act
(17 CFR 240.14a-12(b))

[  ] Pre-commencement communications pursuant to Rule 14d-2(b) under the
Exchange Act (17 CFR 240.14d-2(b))

[  ] Pre-commencement communications pursuant to Rule 13e-4(c) under the
Exchange Act (17 CFR 240.13e-4(c))


     Item 8.01  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 9.01 Financial Statements and Exhibits

     (c) Exhibits:

     Exhibit No. Description

     99.1 Monthly Remittance Statement to the Certificateholders dated as of
     December 27, 2004.

                                    Signatures

               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,
                                  in its capacity as Trustee under the
                                  Pooling and Servicing Agreement on
                                  behalf of Indymac MBS Inc, Registrant


          Date:  Dec 27, 2004               By:  /s/  Katherine M. Wannenmacher
                                            Katherine M. Wannenmacher
                                            Vice President


                                   EXHIBIT INDEX

          DOCUMENT

          99.1 Monthly Remittance Statement to the Certificateholders
          dated as of December 27, 2004.


	IndyMac INDX Mortgage Loan Trust 2004-AR12
	Collateralized Asset-Backed Bonds


	December 27, 2004 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




				Total Number of Pages				22



			CONTACTS

				Administrator: Brent Hoyler
				Direct Phone Number: (714)247-6322
				Address: Deutsche Bank
				1761 E. St. Andrew Place, Santa Ana, CA 92705

				Web Site: https://www.tss.db.com/invr
				Factor Information: (800) 735-7777
				Main Phone Number: (714) 247-6000



ISSUANCE INFORMATION

	Seller:		IndyMac INDX Loan Trust					Cut-Off Date: November 1, 2004
	Certificate Insurer(s):							Closing Date: November 5, 2004
								First Payment Date: December 27, 2004
	Servicer(s):		IndyMac Bank Servicer


								Distribution Date: December 27, 2004
	Underwriter(s):		UBS Securities Underwriter					Record Date: December 24, 2004
			Goldman, Sachs & Co.					November 30, 2004
			RBS Greenwich Capital





						Page 1 of 22					© COPYRIGHT 2004 Deutsche Bank
	IndyMac INDX Mortgage Loan Trust 2004-AR12
	Collateralized Asset-Backed Bonds
	Master Remic Series 2004-AR12
	Certificate Payment Report for December 27, 2004 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	STEP, FLT,	338,000,000.00			338,000,000.00	1,191,262.22	2,551,988.87	3,743,251.09	-	-	335,448,011.13
A-2	STEP, FLT,	37,293,000.00			37,293,000.00	134,669.17	281,571.96	416,241.13	-	-	37,011,428.04
A-X-1	IO, CSTR, N	-			-	250,195.33	-	250,195.33	-	-	-
A-X-2	IO, PO, CST	-			-	37,467.22	-	37,467.22	-	-	-
A-R	R, CSTR, AS	100.00			100.00	0.34	100.00	100.34	-	-	-
B-1	SUB, STEP,	9,080,000.00			9,080,000.00	20,430.00	37,761.12	58,191.12	-	-	9,042,238.88
B-2	SUB, STEP,	7,062,000.00			7,062,000.00	18,537.75	29,368.83	47,906.58	-	-	7,032,631.17
B-3	SUB, STEP,	4,843,000.00			4,843,000.00	16,748.71	20,140.65	36,889.36	-	-	4,822,859.35
B-4	SUB, STEP,	3,834,000.00			3,834,000.00	13,738.50	15,944.51	29,683.01	-	-	3,818,055.49
B-5	SUB, STEP,	2,018,000.00			2,018,000.00	7,231.17	8,392.28	15,623.45	-	-	2,009,607.72
B-6	SUB, STEP,	1,411,628.00			1,411,628.00	5,058.33	5,870.56	10,928.89	-	-	1,405,757.44
P	SUB, EXE	100.00			100.00	2,538.90	-	2,538.90	-	-	100.00


Total		403,541,828.00			403,541,828.00	1,697,877.63	2,951,138.78	4,649,016.41	-	-	400,590,689.22


	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	11/05/04	12/26/04		A-Act/360	45660N5H4	338,000,000.00	1,000.000000	3.524444	7.550263	11.074707	992.449737
A-2	11/05/04	12/26/04		A-Act/360	45660N5J0	37,293,000.00	1,000.000000	3.611111	7.550263	11.161374	992.449737
A-X-1				F-30/360	45660N5K7	375,293,000.00	1,000.000000	0.666667	-	0.666667	1,000.000000
A-X-2				A-30/360	45660N5L5	403,541,728.00	1,000.000000	0.092846	-	0.092846	1,000.000000
A-R				A-30/360	45660N5M3	100.00	1,000.000000	3.400000	1,000.000000	1,003.400000	-
B-1				A-30/360	45660N5N1	9,080,000.00	1,000.000000	2.250000	4.158714	6.408714	995.841286
B-2				A-30/360	45660N5P6	7,062,000.00	1,000.000000	2.625000	4.158713	6.783713	995.841287
B-3				A-30/360	45660N5Q4	4,843,000.00	1,000.000000	3.458334	4.158714	7.617048	995.841286
B-4				A-30/360	45660N6L4	3,834,000.00	1,000.000000	3.583332	4.158714	7.742046	995.841286
B-5				A-30/360	45660N6M2	2,018,000.00	1,000.000000	3.583333	4.158712	7.742044	995.841288
B-6				A-30/360	45660N6N0	1,411,628.00	1,000.000000	3.583333	4.158716	7.742049	995.841284
P				A-30/360		100.00	1,000.000000	25,389.000000	-	25,389.000000	1,000.000000


							Page 2 of 22				© COPYRIGHT 2004 Deutsche Bank
	IndyMac INDX Mortgage Loan Trust 2004-AR12
	Collateralized Asset-Backed Bonds
	Master Remic Series 2004-AR12
	Certificate Payment Report for December 27, 2004 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	338,000,000.00		1,191,262.22		1,146,343.78	1,405,645.09	2,551,988.87	3,743,251.09	-	-	335,448,011.13
A-2	37,293,000.00		134,669.17		126,481.07	155,090.89	281,571.96	416,241.13	-	-	37,011,428.04
A-X-1	-		250,195.33		-	-	-	250,195.33	-	-	-
A-X-2	-		37,467.22		-	-	-	37,467.22	-	-	-
A-R	100.00		0.34		99.58	0.42	100.00	100.34	-	-	-
B-1	9,080,000.00		20,430.00		-	37,761.12	37,761.12	58,191.12	-	-	9,042,238.88
B-2	7,062,000.00		18,537.75		-	29,368.83	29,368.83	47,906.58	-	-	7,032,631.17
B-3	4,843,000.00		16,748.71		-	20,140.65	20,140.65	36,889.36	-	-	4,822,859.35
B-4	3,834,000.00		13,738.50		-	15,944.51	15,944.51	29,683.01	-	-	3,818,055.49
B-5	2,018,000.00		7,231.17		-	8,392.28	8,392.28	15,623.45	-	-	2,009,607.72
B-6	1,411,628.00		5,058.33		-	5,870.56	5,870.56	10,928.89	-	-	1,405,757.44
P	100.00		2,538.90		-	-	-	2,538.90	-	-	100.00


Total	403,541,828.00		1,697,877.63		1,272,924.43	1,678,214.35	2,951,138.78	4,649,016.41	-	-	400,590,689.22


	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	2.44000%	338,000,000.00			1,191,262.22	-	-	-	1,191,262.22	1,191,262.22	-
A-2	2.50000%	37,293,000.00			134,669.17	-	-	-	134,669.17	134,669.17	-
A-X-1	0.80000%	375,293,000.00			250,195.33	-	-	-	250,195.33	250,195.33	-
A-X-2		403,541,728.00			-	-	-	-	-	37,467.22	-
A-R	4.08907%	100.00			0.34	-	-	-	0.34	0.34	-
B-1	2.70000%	9,080,000.00			20,430.00	-	-	-	20,430.00	20,430.00	-
B-2	3.15000%	7,062,000.00			18,537.75	-	-	-	18,537.75	18,537.75	-
B-3	4.08907%	4,843,000.00			16,502.83	-	-	-	16,502.83	16,748.71	-
B-4	4.08907%	3,834,000.00			13,064.59	-	-	-	13,064.59	13,738.50	-
B-5	4.08907%	2,018,000.00			6,876.46	-	-	-	6,876.46	7,231.17	-
B-6	4.08907%	1,411,628.00			4,810.21	-	-	-	4,810.21	5,058.33	-
P		100.00			-	-	-	-	-	2,538.90	-


Total		1,182,376,556.00			1,656,348.90	-	-	-	1,656,348.90	1,697,877.63	-


							Page 3 of 22				© COPYRIGHT 2004 Deutsche Bank
	IndyMac INDX Mortgage Loan Trust 2004-AR12
	Collateralized Asset-Backed Bonds

	Collection Account Report for December 27, 2004 Distribution


	Collection Account Report


SUMMARY								TOTAL

	Principal Collections							2,951,138.77
	Principal Withdrawals							0.00
	Principal Other Accounts							0.00
	TOTAL PRINCIPAL							2,951,138.77

	Interest Collections							1,730,050.71
	Interest Withdrawals							0.00
	Interest Other Accounts							2,538.90
	Interest Fees							(34,711.97)

	TOTAL INTEREST							1,697,877.64

	TOTAL AVAILABLE FUNDS TO BONDHOLDERS							4,649,016.41

	Interest Payable to Bondholders							1,697,877.64


PRINCIPAL - COLLECTIONS								TOTAL

	Scheduled Principal							53,424.45
	Curtailments							432,470.89
	Prepayments in Full							840,453.54
	Repurchases/Substitutions							1,624,789.89
	Liquidations							0.00
	Insurance Principal							0.00
	Other Additional Principal							0.00
	LESS: Delinquent Principal							(37,748.00)
	LESS: Realized Losses							0.00
	PLUS: Recoveries							0.00
	PLUS: Substitution Shortfall Principal							0.00
	PLUS: Principal Loan Adjustments							0.00
	PLUS: Principal Advanced							37,748.00
	TOTAL PRINCIPAL							2,951,138.77


				Page 4 of 22				© COPYRIGHT 2004 Deutsche Bank
	IndyMac INDX Mortgage Loan Trust 2004-AR12
	Collateralized Asset-Backed Bonds

	Collection Account Report for December 27, 2004 Distribution


	Collection Account Report


PRINCIPAL - WITHDRAWALS								TOTAL
SPACE INTENTIONALLY LEFT BLANK


PRINCIPAL - OTHER ACCOUNTS								TOTAL



	TOTAL PRINCIPAL OTHER ACCOUNTS							0.00


INTEREST - COLLECTIONS								TOTAL

	Scheduled Interest							1,498,869.89
	Repurchases/Substitutions							4,852.69
	Liquidations							0.00
	Insurance Interest							0.00
	Other Additional Interest							0.00
	LESS: Prepayment Interest Shortfalls							0.00
	LESS: Delinquent Interest							(1,123,914.31)
	LESS: Interest Realized Losses							0.00
	PLUS: Compensating Interest							0.00
	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							1,029,997.35
	Shortfall reserve deposits							0.00
	Capitalized Interest Deposit							320,245.09
	TOTAL INTEREST							1,730,050.71


				Page 5 of 22				© COPYRIGHT 2004 Deutsche Bank
	IndyMac INDX Mortgage Loan Trust 2004-AR12
	Collateralized Asset-Backed Bonds

	Collection Account Report for December 27, 2004 Distribution


	Collection Account Report


INTEREST - WITHDRAWALS								TOTAL
SPACE INTENTIONALLY LEFT BLANK


INTEREST - OTHER ACCOUNTS								TOTAL

	Prepayment Penalties							2,538.90



	TOTAL INTEREST OTHER ACCOUNTS							2,538.90


INTEREST - FEES								TOTAL

	Current Servicing Fees							32,189.83
	Trustee Fees							2,522.14


	TOTAL INTEREST FEES							34,711.97


				Page 6 of 22				© COPYRIGHT 2004 Deutsche Bank
	IndyMac INDX Mortgage Loan Trust 2004-AR12
	Collateralized Asset-Backed Bonds

	Credit Enhancement Report for December 27, 2004 Distribution


	Credit Enhancement Report


ACCOUNTS								TOTAL

	Carryover Shortfall Reserve Fund Beginning Balance							1,000.00
	Required Reserve Fund Deposit							1,522.62
	Carryover Shortfall Amount							1,522.62
	Carryover Shortfall Reserve Fund Ending Balance							1,000.00


INSURANCE								TOTAL
SPACE INTENTIONALLY LEFT BLANK


STRUCTURAL FEATURES								TOTAL
SPACE INTENTIONALLY LEFT BLANK


				Page 7 of 22				© COPYRIGHT 2004 Deutsche Bank
	IndyMac INDX Mortgage Loan Trust 2004-AR12
	Collateralized Asset-Backed Bonds

	Collateral Report for December 27, 2004 Distribution


	Collateral Report


COLLATERAL								TOTAL
	Loan Count:
	*Original*							1382
	Prior							-
	Prefunding							-
	Scheduled Paid Offs							-
	Full Voluntary Prepayments							(4)
	Repurchases							(6)
	Liquidations							-
	Current							1,372

	*Principal Balance:*
	Original							403,541,727.71
	Prior							-
	Prefunding							-
	Scheduled Principal							(53,424.45)
	Partial and Full Voluntary Prepayments							(1,272,924.43)
	Repurchases							(1,624,789.89)
	Liquidations							-
	Current							400,590,588.94

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 22				© COPYRIGHT 2004 Deutsche Bank
	IndyMac INDX Mortgage Loan Trust 2004-AR12
	Collateralized Asset-Backed Bonds

	Collateral Report for December 27, 2004 Distribution


	Collateral Report


CHARACTERISTICS								TOTAL

	Weighted Average Coupon Original							4.471575%
	Weighted Average Coupon Prior
	Weighted Average Coupon Current							4.471575%
	Weighted Average Months to Maturity Original							358
	Weighted Average Months to Maturity Prior							-
	Weighted Average Months to Maturity Current							358
	Weighted Avg Remaining Amortization Term Original							358
	Weighted Avg Remaining Amortization Term Prior							-
	Weighted Avg Remaining Amortization Term Current							358
	Weighted Average Seasoning Original							2.32
	Weighted Average Seasoning Prior							-
	Weighted Average Seasoning Current							2.32

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 22				© COPYRIGHT 2004 Deutsche Bank
	IndyMac INDX Mortgage Loan Trust 2004-AR12
	Collateralized Asset-Backed Bonds

	Collateral Report for December 27, 2004 Distribution


	Collateral Report


ARM CHARACTERISTICS								TOTAL

	Weighted Average Margin Original							3.065%
	Weighted Average Margin Prior							0.000%
	Weighted Average Margin Current							3.065%
	Weighted Average Max Rate Original							9.847%
	Weighted Average Max Rate Prior							0.000%
	Weighted Average Max Rate Current							9.847%
	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							32,189.83
	Delinquent Servicing Fees							93,916.96
	TOTAL SERVICING FEES							126,106.79

	Total Servicing Fees							126,106.79
	Compensating Interest							0.00
	Delinquent Servicing Fees							(93,916.96)
	COLLECTED SERVICING FEES							32,189.83

	Total Advanced Principal For Current Payment Date							37,748.00
	Total Advanced Interest For Current Payment Date							1,029,997.35
	TOTAL ADVANCES FOR CURRENT PERIOD							1,067,745.35


ADDITIONAL COLLATERAL INFORMATION								TOTAL

	Prepayment Interest Shortfall (PPIS)							0.00
	Compensating Interest							0.00
	Net Prepayment Interest Shortfall (Net PPIS)							0.00

	Weighted Average Net Mortgage Rate							4.089075%

	Current Deferred Interest							205,128.14
	Cumulative Deferred Interest							205,128.14

	Net Deferred Interest							0.00
	Cumulative Net Deferred Interest							0.00



				Page 10 of 22				© COPYRIGHT 2004 Deutsche Bank
	IndyMac INDX Mortgage Loan Trust 2004-AR12
	Collateralized Asset-Backed Bonds

	Delinquency Report for December 27, 2004 Distribution


	Delinquency Report - Total


				<1 PAYMENT	1 PAYMENT	2 PAYMENTS	3+ PAYMENTS	TOTAL
DELINQUENT		Balance		###########	3,554,966.33	-	-	3,554,966.33
		% Balance		74.06%	0.89%	0.00%	0.00%	0.89%
		# Loans		1,005	12	-	-	12
		% # Loans		73.25%	0.87%	0.00%	0.00%	0.87%
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		-	3,554,966.33	-	-	3,554,966.33
		% Balance		0.00%	0.89%	0.00%	0.00%	0.89%
		# Loans		-	12	-	-	12
		% # Loans		0.00%	0.87%	0.00%	0.00%	0.87%
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 22				© COPYRIGHT 2004 Deutsche Bank
	IndyMac INDX Mortgage Loan Trust 2004-AR12
	Collateralized Asset-Backed Bonds

	REO Report for December 27, 2004 Distribution


	REO Report - Mortgage Loans that Become REO During Current Distribution


SUMMARY				LOAN GROUP

Total Loan Count = 0				Loan Group 1 = Group 1; 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 22				© COPYRIGHT 2004 Deutsche Bank
	IndyMac INDX Mortgage Loan Trust 2004-AR12
	Collateralized Asset-Backed Bonds

	Prepayment Report for December 27, 2004 Distribution


	Prepayment Report - Voluntary Prepayments


VOLUNTARY PREPAYMENTS								TOTAL

	*Current*
	Number of Paid in Full Loans							4
	Number of Repurchased Loans							6
	Total Number of Loans Prepaid in Full							10

	Paid in Full Balance							840,453.54
	Repurchased Loans Balance							1,624,789.89
	Curtailments Amount							432,470.89
	Total Prepayment Amount							2,897,714.32

	*Cumulative*
	Number of Paid in Full Loans							4
	Number of Repurchased Loans							6
	Total Number of Loans Prepaid in Full							10

	Paid in Full Balance							840,453.54
	Repurchased Loans Balance							1,624,789.89
	Curtailments Amount							432,470.89
	Total Prepayment Amount							2,897,714.32

SPACE INTENTIONALLY LEFT BLANK


Total Prepayments by Groups (in thousands of dollars)					Total Prepayments (in thousands of dollars)


				Page 13 of 22				© COPYRIGHT 2004 Deutsche Bank
	IndyMac INDX Mortgage Loan Trust 2004-AR12
	Collateralized Asset-Backed Bonds

	Prepayment Report for December 27, 2004 Distribution


	Prepayment Report - Voluntary Prepayments


VOLUNTARY PREPAYMENT RATES								TOTAL

	SMM							0.72%
	3 Months Avg SMM
	12 Months Avg SMM
	Avg SMM Since Cut-off							0.72%

	CPR							8.29%
	3 Months Avg CPR
	12 Months Avg CPR
	Avg CPR Since Cut-off							8.29%

	PSA							1787.41%
	3 Months Avg PSA Approximation
	12 Months Avg PSA Approximation
	Avg PSA Since Cut-off Approximation							1787.41%







CPR by Groups					Total CPR


PSA by Groups					Total PSA


				Page 14 of 22				© COPYRIGHT 2004 Deutsche Bank
	IndyMac INDX Mortgage Loan Trust 2004-AR12
	Collateralized Asset-Backed Bonds

	Prepayment Report for December 27, 2004 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/(0.002*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 22				© COPYRIGHT 2004 Deutsche Bank


	IndyMac INDX Mortgage Loan Trust 2004-AR12
	Collateralized Asset-Backed Bonds

	Prepayment Detail Report for December 27, 2004 Distribution


	Prepayment Detail Report - Loans Prepaid in Full During Current Distribution


SUMMARY						LOAN GROUP

Total Loan Count = 10						Loan Group 1 = Group 1
Total Original Principal Balance = 2,469,588.00
Total Prepayment Amount = 2,465,243.43


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

120231544 1			166,250.00	165,919.73	Dec-29-04	3.995%	GA - 95.00%	Paid Off - 360	Sep-27-04
120333922 1			393,750.00	392,983.19	Dec-16-04	4.445%	NH - 75.00%	Paid Off - 360	Sep-29-04
120362350 1			136,500.00	136,234.17	Dec-09-04	4.445%	CA - 70.00%	Paid Off - 360	Sep-24-04
120363237 1			145,600.00	145,316.45	Dec-01-04	4.445%	CA - 70.00%	Paid Off - 360	Sep-24-04
120083663 1			650,000.00	648,451.01	Dec-30-04	4.445%	NY - 74.97%	Repur/Subs - 360	Oct-08-04
120104994 1			133,696.00	133,389.73	Dec-30-04	4.895%	FL - 80.00%	Repur/Subs - 360	Oct-01-04
120192765 1			342,000.00	341,305.90	Dec-30-04	4.145%	NJ - 90.00%	Repur/Subs - 360	Sep-30-04
120228347 1			340,000.00	340,000.00	Dec-30-04	1.000%	NJ - 80.00%	Repur/Subs - 360	Oct-07-04
120283403 1			73,292.00	73,143.25	Dec-30-04	4.870%	PA - 95.00%	Repur/Subs - 360	Sep-28-04
120283501 1			88,500.00	88,500.00	Dec-30-04	2.000%	RI - 46.58%	Repur/Subs - 360	Oct-07-04


					Page 16 of 22				© COPYRIGHT 2004 Deutsche Bank
	IndyMac INDX Mortgage Loan Trust 2004-AR12
	Collateralized Asset-Backed Bonds

	Realized Loss Report for December 27, 2004 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
	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 22				© COPYRIGHT 2004 Deutsche Bank
	IndyMac INDX Mortgage Loan Trust 2004-AR12
	Collateralized Asset-Backed Bonds

	Realized Loss Report for December 27, 2004 Distribution


	Realized Loss Report - Collateral


DEFAULT SPEEDS								TOTAL

	MDR							0.00%
	3 Months Avg MDR
	12 Months Avg MDR
	Avg MDR Since Cut-off							0.00%

	CDR							0.00%
	3 Months Avg CDR
	12 Months Avg CDR
	Avg CDR Since Cut-off							0.00%

	SDA							0.00%
	3 Months Avg SDA Approximation
	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 22				© COPYRIGHT 2004 Deutsche Bank
	IndyMac INDX Mortgage Loan Trust 2004-AR12
	Collateralized Asset-Backed Bonds

	Realized Loss Report for December 27, 2004 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 22				© COPYRIGHT 2004 Deutsche Bank


	IndyMac INDX Mortgage Loan Trust 2004-AR12
	Collateralized Asset-Backed Bonds

	Realized Loss Detail Report for December 27, 2004 Distribution


	Realized Loss Detail Report - Loans Liquidated During Current Distribution

SUMMARY							LOAN GROUP
Total Loan Count Current Losses = 0
Total Loan Count Revisions = 0						Loan Group 1 = Group 1
Total Prior Principal Balance = 0.00
Total Current Realized Loss Amount = 0.00
Total Revisions Amount = 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			Current	State &		Prior	Realized		Cumulative
&		Loan	Note	LTV at	Original	Principal	Loss/(Gain)	Realized	Realized
Loan Group		Status	Rate	Origination	Term	Balance	Revisions	Loss/(Gain)	Loss/(Gain)
SPACE INTENTIONALLY LEFT BLANK


					Page 20 of 22				© COPYRIGHT 2004 Deutsche Bank
	IndyMac INDX Mortgage Loan Trust 2004-AR12
	Collateralized Asset-Backed Bonds

	Triggers, Adj. Rate Cert. and Miscellaneous Report for December 27, 2004 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


ADJUSTABLE RATE CERTIFICATE INFORMATION								TOTAL
SPACE INTENTIONALLY LEFT BLANK


ADDITIONAL INFORMATION								TOTAL

	Current Senior Percentage							92.999825%
	Next Senior Percentage							92.977581%
	Current Subordinate Percentage							7.000175%
	Next Subordinate Percentage							7.022419%
	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%


				Page 21 of 22				© COPYRIGHT 2004 Deutsche Bank
	IndyMac INDX Mortgage Loan Trust 2004-AR12
	Collateralized Asset-Backed Bonds

	Other Related Information for December 27, 2004 Distribution


	Other Related Information


ADDITIONAL INFORMATION								TOTAL

	Scheduled principal
	1 Month Prior							53,424.45
	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

	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 22				© COPYRIGHT 2004 Deutsche Bank

Indymac INDX Mortgage Loan Trust 2004-AR12 8-K