IndyMac IMSC Mortgage Loan Trust 2007-AR1

Mortgage Pass-Through Certificates

November 26, 2007 Distribution

External Parties

Table of Contents

Page

Seller

1. Certificate Payment Report

IndyMac Bank, F.S.B.

2. Collection Account Report

3. Credit Enhancement Report

Servicer(s)

4. Collateral Report

IndyMac Bank, F.S.B.

5. Delinquency Report

6. REO Report

Underwriter(s)

7. Foreclosure Report

Credit Suisse Securities LLC

8. Prepayment Report

9. Prepayment Detail Report

10. Realized Loss Report

11. Realized Loss Detail Report

12. Triggers and Adj. Cert. Report

13. Other Related Information

Total Number of Pages

Dates

Contacts

Cut-Off Date:

June 01, 2007

Jennifer Hermansader

Close Date:

June 28, 2007

Administrator

First Distribution Date:

July 25, 2007

(714) 247-6258

Jennifer.Vandyne@db.com

Address:

Distribution Date:

November 26, 2007

1761 East St. Andrew Place, Santa Ana, CA 92705

Record Date:

October 31, 2007

Factor Information:

(800) 735-7777

Main Phone Number:

(714) 247-6000

Determination Date:

November 15, 2007

https://tss.sfs.db.com/investpublic

Page 1 of 29

IndyMac IMSC Mortgage Loan Trust 2007-AR1



Mortgage Pass-Through Certificates
Mortgage Pass-Through Certificates
November 26, 2007 Distribution

Certificate Payment Report
Current Period Distribution - MASTER REMIC
			Prior						Current
			Prior

	Class	Original	Principal			Total	Realized	Deferred	Principal

Class	Type	Face Value	Balance	Interest	Principal	Distribution	Loss	Interest	Balance
			(1)	(2)	(3)	(4)=(2)+(3)	(5)	(6)	(7)=(1)-(3)-(5)+(6)
1-A-1	SR	33,045,000.00	32,258,093.86	162,052.04	414,663.44	576,715.48	0.00	0.00	31,843,430.42
1-A-1	SR	33,045,000.00	32,258,093.86	162,052.04	414,663.44	576,715.48	0.00	0.00	31,843,430.42
1-A-2	SR/SUP	3,670,000.00	3,582,605.68	17,997.61	46,052.80	64,050.41	0.00	0.00	3,536,552.88
2-A-1	SR	485,185,000.00	461,300,867.90	2,534,613.66	4,683,117.19	7,217,730.85	0.00	0.00	456,617,750.71
2-A-2	SR/SUP	52,700,000.00	50,105,744.69	275,305.58	508,672.52	783,978.10	0.00	0.00	49,597,072.17
3-A-1	SR	53,655,000.00	51,806,982.90	268,583.24	348,360.35	616,943.59	0.00	0.00	51,458,622.55
A-R	SR/RES	100.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00
B-1	SUB	25,757,000.00	25,740,834.05	140,042.13	103,310.34	243,352.47	0.00	0.00	25,637,523.71
B-2	SUB	14,270,000.00	14,261,043.68	77,586.72	57,236.42	134,823.14	0.00	0.00	14,203,807.26
B-3	SUB	7,658,000.00	7,653,193.58	41,636.94	30,715.94	72,352.88	0.00	0.00	7,622,477.64
B-4	SUB/NOF	8,701,000.00	8,695,538.97	47,307.78	34,899.38	82,207.16	0.00	0.00	8,660,639.59
B-5	SUB/NOF	6,265,000.00	6,261,067.88	34,063.13	25,128.68	59,191.81	0.00	0.00	6,235,939.20
B-6	SUB/NOF	5,221,417.00	5,218,139.88	28,389.11	20,942.91	49,332.02	0.00	0.00	5,197,196.97
P-1	NOF	100.00	100.00	2,168.58	0.00	2,168.58	0.00	0.00	100.00
P-2	NOF	100.00	100.00	10,370.01	0.00	10,370.01	0.00	0.00	100.00
L	NOF	0.00	0.00	19,387.72	0.00	19,387.72	0.00	0.00	0.00


Total		696,127,717.00	666,884,313.07	3,659,504.25	6,273,099.97	9,932,604.22	0.00	0.00	660,611,213.10
Total




Interest Accrual Detail Current Period Factor Information per $1,000 of Original Face Value
					Orig. Principal	Prior				Current
					Orig. Principal	Prior				Current
	Period	Period			(with Notional)	Principal			Total	Principal
Class	Starting	Ending	Method	Cusip	Balance	Balance	Interest	Principal	Distribution	Balance
			Method
					(1)	(1)	(2)	(3)	(4)=(2)+(3)	(5)

1-A-1	10/01/07	10/30/07	A-30/360	456672AA2	33,045,000.00	976.186832	4.903981	12.548447	17.452428	963.638385
1-A-1	10/01/07	10/30/07	A-30/360	456672AA2	33,045,000.00	976.186832	4.903981	12.548447	17.452428	963.638385
1-A-2	10/01/07	10/30/07	A-30/360	456672AB0	3,670,000.00	976.186834	4.903981	12.548447	17.452428	963.638387
2-A-1	10/01/07	10/30/07	A-30/360	456672AC8	485,185,000.00	950.773144	5.224015	9.652230	14.876245	941.120914
2-A-2	10/01/07	10/30/07	A-30/360	456672AD6	52,700,000.00	950.773144	5.224015	9.652230	14.876245	941.120914
3-A-1	10/01/07	10/30/07	A-30/360	456672AQ7	53,655,000.00	965.557411	5.005745	6.492598	11.498343	959.064813
A-R	10/01/07	10/30/07	A-30/360	456672AE4	100.00	0.000000	0.000000	0.000000	0.000000	0.000000
B-1	10/01/07	10/30/07	A-30/360	456672AF1	25,757,000.00	999.372367	5.437051	4.010962	9.448013	995.361405
B-2	10/01/07	10/30/07	A-30/360	456672AG9	14,270,000.00	999.372367	5.437051	4.010961	9.448013	995.361406
B-3	10/01/07	10/30/07	A-30/360	456672AH7	7,658,000.00	999.372366	5.437051	4.010961	9.448013	995.361405
B-4	10/01/07	10/30/07	A-30/360	456672AJ3	8,701,000.00	999.372368	5.437051	4.010962	9.448013	995.361406
B-5	10/01/07	10/30/07	A-30/360	456672AK0	6,265,000.00	999.372367	5.437052	4.010962	9.448014	995.361405
B-6	10/01/07	10/30/07	A-30/360	456672AL8	5,221,417.00	999.372370	5.437051	4.010963	9.448014	995.361407
P-1		456672AM6	100.00	1,000.000000	21,685.800000	0.000000	21,685.800000	1,000.000000
P-2		456672AN4	100.00	1,000.000000	103,700.100000	0.000000	103,700.100000	1,000.000000
L		456672AP9	0.00	0.000000	0.000000	0.000000	0.000000	0.000000




Page 2 of 29

IndyMac IMSC Mortgage Loan Trust 2007-AR1



Mortgage Pass-Through Certificates
Mortgage Pass-Through Certificates
November 26, 2007 Distribution


Distribution to Date - MASTER REMIC
									Current


	Original		Unscheduled	Scheduled	Total	Total	Realized	Deferred	Principal

Class	Face Value	Interest	Principal	Principal	Principal	Distribution	Loss	Interest	Balance
(1)	(2)	(3)	(4)	(5)=(3)+(4)	(6)=(2)+(5)	(7)	(8)	(9)=(1)-(5)-(7)+(8)
1-A-1	33,045,000.00	821,743.38	1,187,643.43	13,926.15	1,201,569.58	2,023,312.96	0.00	0.00	31,843,430.42
1-A-2	3,670,000.00	91,263.38	131,900.48	1,546.64	133,447.12	224,710.50	0.00	0.00	3,536,552.88
2-A-1	485,185,000.00	12,970,620.86	26,089,930.47	2,477,318.82	28,567,249.29	41,537,870.15	0.00	0.00	456,617,750.71
2-A-2	52,700,000.00	1,408,847.59	2,833,845.51	269,082.31	3,102,927.83	4,511,775.42	0.00	0.00	49,597,072.17
3-A-1	53,655,000.00	1,375,469.44	2,176,427.21	19,950.24	2,196,377.45	3,571,846.89	0.00	0.00	51,458,622.55
A-R	100.00	0.50	0.00	0.00	100.00	100.50	0.00	0.00	0.00
B-1	25,757,000.00	701,243.37	0.00	119,476.29	119,476.29	820,719.66	0.00	0.00	25,637,523.71
B-2	14,270,000.00	388,505.76	0.00	66,192.74	66,192.74	454,698.50	0.00	0.00	14,203,807.26
B-3	7,658,000.00	208,491.74	0.00	35,522.36	35,522.36	244,014.10	0.00	0.00	7,622,477.64
B-4	8,701,000.00	236,887.78	0.00	40,360.41	40,360.41	277,248.19	0.00	0.00	8,660,639.59
B-5	6,265,000.00	170,566.83	0.00	29,060.80	29,060.80	199,627.63	0.00	0.00	6,235,939.20
B-6	5,221,417.00	142,154.91	0.00	24,220.03	24,220.03	166,374.94	0.00	0.00	5,197,196.97
P-1	100.00	35,513.06	0.00	0.00	0.00	35,513.06	0.00	0.00	100.00
P-2	100.00	44,086.52	0.00	0.00	0.00	44,086.52	0.00	0.00	100.00
L	0.00	36,227.25	0.00	0.00	0.00	36,227.25	0.00	0.00	0.00


Total	696,127,717.00	18,631,622.37	32,419,747.10	3,096,656.79	35,516,503.90	54,148,126.27	0.00	0.00	660,611,213.10


Interest Detail - MASTER REMIC
	Pass	Prior Principal		Non-	Prior	Unscheduled		Paid or	Current
	Pass	Prior Principal		Non-	Prior	Unscheduled		Paid or

	Through	(with Notional)	Accrued	Supported	Unpaid	Interest	Optimal	Deferred	Unpaid

Class	Rate	Balance	Interest	Interest SF	Interest	Adjustment	Interest	Interest	Interest
			(1)	(2)	(3)	(4)	(5)=(1)-(2)+(3)+(4)	(6)	(7)=(5)-(6)
1-A-1	6.02833%	32,258,093.86	162,052.04	0.00	0.00	0.00	162,052.04	162,052.04	0.00
1-A-2	6.02833%	3,582,605.68	17,997.61	0.00	0.00	0.00	17,997.61	17,997.61	0.00
2-A-1	6.59339%	461,300,867.90	2,534,613.66	0.00	0.00	0.00	2,534,613.66	2,534,613.66	0.00
2-A-2	6.59339%	50,105,744.69	275,305.58	0.00	0.00	0.00	275,305.58	275,305.58	0.00
3-A-1	6.22117%	51,806,982.90	268,583.24	0.00	0.00	0.00	268,583.24	268,583.24	0.00
A-R	0.00000%	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00
B-1	6.52856%	25,740,834.05	140,042.13	0.00	0.00	0.00	140,042.13	140,042.13	0.00
B-2	6.52856%	14,261,043.68	77,586.72	0.00	0.00	0.00	77,586.72	77,586.72	0.00
B-3	6.52856%	7,653,193.58	41,636.94	0.00	0.00	0.00	41,636.94	41,636.94	0.00
B-4	6.52856%	8,695,538.97	47,307.78	0.00	0.00	0.00	47,307.78	47,307.78	0.00
B-5	6.52856%	6,261,067.88	34,063.13	0.00	0.00	0.00	34,063.13	34,063.13	0.00
B-6	6.52856%	5,218,139.88	28,389.11	0.01	0.00	0.00	28,389.10	28,389.11	0.00
P-1	0.00000%	100.00	0.00	0.00	0.00	0.00	0.00	2,168.58	0.00
P-2	0.00000%	100.00	0.00	0.00	0.00	0.00	0.00	10,370.01	0.00
L	0.00000%	0.00	0.00	0.00	0.00	0.00	0.00	19,387.72	0.00


Total		666,884,313.07	3,627,577.94	0.01	0.00	0.00	3,627,577.93	3,659,504.25	0.00



Page 3 of 29

IndyMac IMSC Mortgage Loan Trust 2007-AR1



Mortgage Pass-Through Certificates
Mortgage Pass-Through Certificates
November 26, 2007 Distribution

Collection Account Report
SUMMARY

	Group 3	Group 2	Group 1	Total
Principal Collections	348,809.98	5,463,226.91	461,063.08	6,273,099.97
Principal Withdrawals	0.00	0.00	0.00	0.00
Principal Other Accounts	0.00	0.00	0.00	0.00
TOTAL NET PRINCIPAL	348,809.98	5,463,226.91	461,063.08	6,273,099.97
Interest Collections	312,411.57	3,255,808.74	210,286.83	3,778,507.14
Interest Withdrawals	-0.00	-0.00	-0.00	-0.00
Interest Other Accounts	1,926.52	28,682.51	1,317.28	31,926.31
Interest Fees	-13,785.54	-126,825.03	-10,318.62	-150,929.20
TOTAL NET INTEREST	300,552.55	3,157,666.22	201,285.48	3,659,504.25
TOTAL AVAILABLE FUNDS FOR DISTRIBUTION	649,362.53	8,620,893.13	662,348.56	9,932,604.22




PRINCIPAL - COLLECTIONS

	Group 3	Group 2	Group 1	Total
Scheduled Principal Received	4,469.31	43,941.12	3,482.03	51,892.46
Curtailments	102,340.67	17,633.17	1,862.89	121,836.73
Prepayments In Full	242,000.00	2,783,678.51	455,718.16	3,481,396.67
Repurchased/Substitutions	0.00	2,617,974.11	0.00	2,617,974.11
Liquidations	0.00	0.00	0.00	0.00
Insurance Principal	0.00	0.00	0.00	0.00
Other Additional Principal	0.00	0.00	0.00	0.00
Delinquent Principal	-1,386.47	-14,903.05	-468.79	-16,758.31
Realized Losses	-0.00	-0.00	-0.00	-0.00
Advanced Principal	1,386.47	14,903.05	468.79	16,758.31
TOTAL PRINCIPAL COLLECTED	348,809.98	5,463,226.91	461,063.08	6,273,099.97




PRINCIPAL - WITHDRAWALS

SPACE INTENTIONALLY LEFT BLANK




PRINCIPAL - OTHER ACCOUNTS

	Group 3	Group 2	Group 1	Total
TOTAL PRINCIPAL OTHER ACCOUNTS	0.00	0.00	0.00	0.00






Page 4 of 29

IndyMac IMSC Mortgage Loan Trust 2007-AR1



Mortgage Pass-Through Certificates
Mortgage Pass-Through Certificates
November 26, 2007 Distribution


INTEREST - COLLECTIONS

	Group 3	Group 2	Group 1	Total
Scheduled Interest	316,947.49	3,295,877.16	212,734.84	3,825,559.49
Repurchased/Substitution Interest	0.00	15,737.70	0.00	15,737.70
Liquidation Interest	0.00	0.00	0.00	0.00
Insurance Interest	0.00	0.00	0.00	0.00
Other Additional Interest	0.00	0.00	0.00	0.00
Prepayment Interest Shortfalls	-513.41	-3,716.67	-0.00	-4,230.08
Delinquent Interest	-81,172.66	-1,077,523.74	-43,464.78	-1,202,161.18
Compensating Interest	513.41	3,716.67	0.00	4,230.08
Civil Relief Act Shortfalls	-0.00	-0.00	-0.00	-0.00
Interest Advanced	76,636.74	1,021,717.62	41,016.76	1,139,371.12
Interest Realized Loss	-0.00	-0.00	-0.00	-0.00
TOTAL INTEREST COLLECTED	312,411.57	3,255,808.74	210,286.83	3,778,507.14




INTEREST - WITHDRAWALS

SPACE INTENTIONALLY LEFT BLANK




INTEREST - OTHER ACCOUNTS
INTEREST - OTHER ACCOUNTS
	Group 3	Group 2	Group 1	Total

Late payment charges.	1,926.52	16,143.92	1,317.28	19,387.72
Hard Prepayment charges.	0.00	2,168.58	0.00	2,168.58
Soft Prepayment charges.	0.00	10,370.01	0.00	10,370.01
TOTAL INTEREST OTHER ACCOUNTS	1,926.52	28,682.51	1,317.28	31,926.31

Late payment charges Waived.	0.00	958.69	0.00	958.69




INTEREST FEES
INTEREST FEES
	Group 3	Group 2	Group 1	Total
Current Servicing Fees	13,464.68	122,155.29	9,991.26	145,611.23
Trustee Fees	264.01	2,610.10	182.44	3,056.55
PMI Insurer Fee	2,059.64	2,059.64	144.92	2,261.42
TOTAL INTEREST FEES	13,785.54	126,825.03	10,318.62	150,929.20



Page 5 of 29

IndyMac IMSC Mortgage Loan Trust 2007-AR1

Mortgage Pass-Through Certificates

November 26, 2007 Distribution

Credit Enhancement Report

ACCOUNTS

Distribution Account

Beginning Account Balance

0.00

Amount Deposited

9,935,660.77

Amount Withdrawn

9,935,660.77

Ending Account Balance

0.00

INSURANCE

SPACE INTENTIONALLY LEFT BLANK

STRUCTURAL FEATURES

SPACE INTENTIONALLY LEFT BLANK

Page 6 of 29

IndyMac IMSC Mortgage Loan Trust 2007-AR1



Mortgage Pass-Through Certificates
Mortgage Pass-Through Certificates
November 26, 2007 Distribution

Collateral Report


COLLATERAL



		Group 3	Group 2	Group 1	Total



Loan Count:
Loan Count:


Original	148	1,678	137	1,963
Prior	145	1,609	135	1,889
Prefunding	0	0	0	0
Scheduled Paid Offs	-0	-0	-0	-0
Full Voluntary Prepayments	-1	-11	-2	-14
Repurchases	-0	-5	-0	-5
Liquidations	-0	-0	-0	-0
Current	144	1,593	133	1,870
Principal Balance:


Original	59,451,681.41	595,994,396.85	40,681,438.74	696,127,517.00
Prior	57,601,929.34	569,476,495.07	39,805,688.66	666,884,113.07
Prefunding	0.00	0.00	0.00	0.00
Scheduled Principal	-4,469.31	-43,941.12	-3,482.03	-51,892.46
Partial Prepayments	-102,340.67	-17,633.17	-1,862.89	-121,836.73
Full Voluntary Prepayments	-242,000.00	-2,783,678.51	-455,718.16	-3,481,396.67
Repurchases	-0.00	-2,617,974.11	-0.00	-2,617,974.11
Liquidations	-0.00	-0.00	-0.00	-0.00
Current	57,253,119.36	564,013,268.16	39,344,625.58	660,611,013.10






PREFUNDING

SPACE INTENTIONALLY LEFT BLANK






Page 7 of 29

IndyMac IMSC Mortgage Loan Trust 2007-AR1

Mortgage Pass-Through Certificates

November 26, 2007 Distribution



CHARACTERISTICS
CHARACTERISTICS

	Group 3	Group 2	Group 1	Total
Weighted Average Coupon Original	6.62642%	6.99693%	6.41841%	6.93148%
Weighted Average Coupon Prior	6.61339%	6.97887%	6.41325%	6.91351%
Weighted Average Coupon Current	6.60285%	6.97823%	6.41320%	6.91208%
Weighted Average Months to Maturity Original	355	355	355	355
Weighted Average Months to Maturity Prior	353	352	352	352
Weighted Average Months to Maturity Current	351	351	351	351
Weighted Avg Remaining Amortization Term Original	355	356	355	356
Weighted Avg Remaining Amortization Term Prior	353	353	352	353
Weighted Avg Remaining Amortization Term Current	351	352	351	352
Weighted Average Seasoning Original	4.32	4.59	4.97	4.59
Weighted Average Seasoning Prior	7.26	7.57	7.98	7.57
Weighted Average Seasoning Current	8.26	8.57	8.97	8.57

Page 8 of 29

IndyMac IMSC Mortgage Loan Trust 2007-AR1

Mortgage Pass-Through Certificates

November 26, 2007 Distribution



ARM CHARACTERISTICS
ARM CHARACTERISTICS

	Group 3	Group 2	Group 1	Total
Weighted Average Margin Original	2.43816%	2.57400%	3.16083%	2.59669%
Weighted Average Margin Prior	2.43836%	2.57498%	3.18057%	2.59901%
Weighted Average Margin Current	2.44095%	2.57484%	3.18060%	2.59943%
Weighted Average Max Rate Original	11.96977%	12.54579%	12.21631%	12.47734%
Weighted Average Max Rate Prior	11.95650%	12.52903%	12.22361%	12.46109%
Weighted Average Max Rate Current	11.93685%	12.52830%	12.22354%	12.45902%
Weighted Average Min Rate Original	2.44180%	3.19382%	3.59080%	3.15279%
Weighted Average Min Rate Prior	2.44198%	3.19284%	3.61980%	3.15282%
Weighted Average Min Rate Current	2.44460%	3.19449%	3.61982%	3.15510%
Weighted Average Cap Up Original	1.77690%	1.59890%	1.61158%	1.61484%
Weighted Average Cap Up Prior	1.77307%	1.60110%	1.62000%	1.61719%
Weighted Average Cap Up Current	1.76995%	1.60176%	1.61997%	1.61737%
Weighted Average Cap Down Original	1.77690%	1.59890%	1.61158%	1.61484%
Weighted Average Cap Down Prior	1.77307%	1.60110%	1.62000%	1.61719%
Weighted Average Cap Down Current	1.76995%	1.60176%	1.61997%	1.61737%





Page 9 of 29

IndyMac IMSC Mortgage Loan Trust 2007-AR1



Mortgage Pass-Through Certificates
Mortgage Pass-Through Certificates
November 26, 2007 Distribution


SERVICING FEES & ADVANCES
SERVICING FEES & ADVANCES

	Group 3	Group 2	Group 1	Total




Current Servicing Fees	13,464.68	122,155.29	9,991.26	145,611.23
Delinquent Servicing Fees	4,535.93	55,806.12	2,448.01	62,790.06
TOTAL SERVICING FEES	18,000.60	177,961.41	12,439.28	208,401.29


Total Servicing Fees	18,000.60	177,961.41	12,439.28	208,401.29
Compensating Interest	-513.41	-3,716.67	-0.00	-4,230.08
Delinquent Servicing Fees	-4,535.93	-55,806.12	-2,448.01	-62,790.06
COLLECTED SERVICING FEES	12,951.27	118,438.62	9,991.26	141,381.15


Total Advanced Interest	76,636.74	1,021,717.62	41,016.76	1,139,371.12
Total Advanced Principal	1,386.47	14,903.05	468.79	16,758.31
Aggregate Advances with respect to this Distribution	78,023.21	1,036,620.67	41,485.55	1,156,129.43





ADDITIONAL COLLATERAL INFORMATION
ADDITIONAL COLLATERAL INFORMATION
	Group 3	Group 2	Group 1	Total
Prepayment Interest Shortfall (PPIS)	513.41	3,716.67	0.00	4,230.08
Compensating Interest	(513.41)	(3,716.67)	0.00	(4,230.08)
Net Prepayment Interest Shortfall (PPIS)	0.00	0.00	0.00	0.00

Weighted Average Net Mortgage Rate	6.221167%	6.593390%	6.028330%	6.527511%
Market Value of outstanding REO properties.*

* Information not available with Trustee.





Page 10 of 29

IndyMac IMSC Mortgage Loan Trust 2007-AR1



Mortgage Pass-Through Certificates
Mortgage Pass-Through Certificates
November 26, 2007 Distribution

Delinquency Report

TOTAL
		< 1 PAYMENT	1 PAYMENT	2 PAYMENTS	3+ PAYMENTS	TOTAL
DELINQUENT	Balance		26,206,380.13	17,804,753.81	17,289,187.58	61,300,321.52
	% Balance		3.97%	2.70%	2.62%	9.28%
	# Loans		90	47	46	183
	% # Loans		4.81%	2.51%	2.46%	9.79%
FORECLOSURE	Balance	0.00	0.00	0.00	14,270,839.27	14,270,839.27
	% Balance	0.00%	0.00%	0.00%	2.16%	2.16%
	# Loans	0	0	0	38	38
	% # Loans	0.00%	0.00%	0.00%	2.03%	2.03%
BANKRUPTCY	Balance	0.00	0.00	0.00	0.00	0.00
	% Balance	0.00%	0.00%	0.00%	0.00%	0.00%
	# Loans	0	0	0	0	0
	% # Loans	0.00%	0.00%	0.00%	0.00%	0.00%
REO	Balance	0.00	0.00	0.00	332,000.00	332,000.00
	% Balance	0.00%	0.00%	0.00%	0.05%	0.05%
	# Loans	0	0	0	1	1
	% # Loans	0.00%	0.00%	0.00%	0.05%	0.05%
TOTAL	Balance	0.00	26,206,380.13	17,804,753.81	31,892,026.85	75,903,160.79
	% Balance	0.00%	3.97%	2.70%	4.83%	11.49%
	# Loans	0	90	47	85	222
	% # Loans	0.00%	4.81%	2.51%	4.55%	11.87%

Page 11 of 29

IndyMac IMSC Mortgage Loan Trust 2007-AR1



Mortgage Pass-Through Certificates
Mortgage Pass-Through Certificates
November 26, 2007 Distribution


GROUP 1
		< 1 PAYMENT	1 PAYMENT	2 PAYMENTS	3+ PAYMENTS	TOTAL
DELINQUENT	Balance		1,077,018.00	364,827.34	622,242.00	2,064,087.34
	% Balance		2.74%	0.93%	1.58%	5.25%
	# Loans		5	2	2	9
	% # Loans		3.76%	1.50%	1.50%	6.77%
FORECLOSURE	Balance	0.00	0.00	0.00	713,920.00	713,920.00
	% Balance	0.00%	0.00%	0.00%	1.81%	1.81%
	# Loans	0	0	0	2	2
	% # Loans	0.00%	0.00%	0.00%	1.50%	1.50%
BANKRUPTCY	Balance	0.00	0.00	0.00	0.00	0.00
	% Balance	0.00%	0.00%	0.00%	0.00%	0.00%
	# Loans	0	0	0	0	0
	% # Loans	0.00%	0.00%	0.00%	0.00%	0.00%
REO	Balance	0.00	0.00	0.00	0.00	0.00
	% Balance	0.00%	0.00%	0.00%	0.00%	0.00%
	# Loans	0	0	0	0	0
	% # Loans	0.00%	0.00%	0.00%	0.00%	0.00%
TOTAL	Balance	0.00	1,077,018.00	364,827.34	1,336,162.00	2,778,007.34
	% Balance	0.00%	2.74%	0.93%	3.40%	7.06%
	# Loans	0	5	2	4	11
	% # Loans	0.00%	3.76%	1.50%	3.01%	8.27%

Page 12 of 29

IndyMac IMSC Mortgage Loan Trust 2007-AR1



Mortgage Pass-Through Certificates
Mortgage Pass-Through Certificates
November 26, 2007 Distribution


GROUP 2
		< 1 PAYMENT	1 PAYMENT	2 PAYMENTS	3+ PAYMENTS	TOTAL
DELINQUENT	Balance		24,387,621.26	15,749,820.64	15,575,248.09	55,712,689.99
	% Balance		4.32%	2.79%	2.76%	9.88%
	# Loans		82	42	40	164
	% # Loans		5.15%	2.64%	2.51%	10.30%
FORECLOSURE	Balance	0.00	0.00	0.00	13,556,919.27	13,556,919.27
	% Balance	0.00%	0.00%	0.00%	2.40%	2.40%
	# Loans	0	0	0	36	36
	% # Loans	0.00%	0.00%	0.00%	2.26%	2.26%
BANKRUPTCY	Balance	0.00	0.00	0.00	0.00	0.00
	% Balance	0.00%	0.00%	0.00%	0.00%	0.00%
	# Loans	0	0	0	0	0
	% # Loans	0.00%	0.00%	0.00%	0.00%	0.00%
REO	Balance	0.00	0.00	0.00	332,000.00	332,000.00
	% Balance	0.00%	0.00%	0.00%	0.06%	0.06%
	# Loans	0	0	0	1	1
	% # Loans	0.00%	0.00%	0.00%	0.06%	0.06%
TOTAL	Balance	0.00	24,387,621.26	15,749,820.64	29,464,167.36	69,601,609.26
	% Balance	0.00%	4.32%	2.79%	5.22%	12.34%
	# Loans	0	82	42	77	201
	% # Loans	0.00%	5.15%	2.64%	4.83%	12.62%

Page 13 of 29

IndyMac IMSC Mortgage Loan Trust 2007-AR1



Mortgage Pass-Through Certificates
Mortgage Pass-Through Certificates
November 26, 2007 Distribution


GROUP 3
		< 1 PAYMENT	1 PAYMENT	2 PAYMENTS	3+ PAYMENTS	TOTAL
DELINQUENT	Balance		741,740.87	1,690,105.83	1,091,697.49	3,523,544.19
	% Balance		1.30%	2.95%	1.91%	6.15%
	# Loans		3	3	4	10
	% # Loans		2.08%	2.08%	2.78%	6.94%
FORECLOSURE	Balance	0.00	0.00	0.00	0.00	0.00
	% Balance	0.00%	0.00%	0.00%	0.00%	0.00%
	# Loans	0	0	0	0	0
	% # Loans	0.00%	0.00%	0.00%	0.00%	0.00%
BANKRUPTCY	Balance	0.00	0.00	0.00	0.00	0.00
	% Balance	0.00%	0.00%	0.00%	0.00%	0.00%
	# Loans	0	0	0	0	0
	% # Loans	0.00%	0.00%	0.00%	0.00%	0.00%
REO	Balance	0.00	0.00	0.00	0.00	0.00
	% Balance	0.00%	0.00%	0.00%	0.00%	0.00%
	# Loans	0	0	0	0	0
	% # Loans	0.00%	0.00%	0.00%	0.00%	0.00%
TOTAL	Balance	0.00	741,740.87	1,690,105.83	1,091,697.49	3,523,544.19
	% Balance	0.00%	1.30%	2.95%	1.91%	6.15%
	# Loans	0	3	3	4	10
	% # Loans	0.00%	2.08%	2.08%	2.78%	6.94%

Page 14 of 29

IndyMac IMSC Mortgage Loan Trust 2007-AR1

Mortgage Pass-Through Certificates

November 26, 2007 Distribution

REO Report

Loan Number

Original

Stated

Current

State &

First

Principal

Paid to

Note

LTV at

Original

Payment

Loan Group

Balance

Date

Rate

Origination

Term

Date

Became REO Property this Period:

125336330 2

332,000.00

01-May-2007

8.000%

GA - 80.00%

360

01-Feb-2007

TOTAL

332,000.00

Page 15 of 29

IndyMac IMSC Mortgage Loan Trust 2007-AR1



Mortgage Pass-Through Certificates
Mortgage Pass-Through Certificates
November 26, 2007 Distribution

Foreclosure Report
Loan Number	Original	Stated		Current	State &		First
Loan Number	Original	Stated		Current	State &		First
&	Principal	Principal	Paid to	Note	LTV at	Original	Payment
Loan Group	Balance	Balance	Date	Rate	Origination	Term	Date
					Origination

Became Foreclosure Property this Period:
6089459 2	735,000.00	729,525.62	01-May-2007	7.625%	FL - 75.00%	360	01-Feb-2007
6097551 2	440,000.00	440,000.00	01-Jun-2007	8.000%	FL - 80.00%	360	01-Mar-2007
6098464 2	231,920.00	231,920.00	01-May-2007	8.625%	CT - 80.00%	360	01-Mar-2007
6098928 2	292,000.00	292,000.00	01-Jun-2007	7.500%	CA - 80.00%	360	01-Mar-2007
6098929 2	216,000.00	215,998.82	01-Jun-2007	7.875%	WA - 80.00%	360	01-Mar-2007
6099068 2	481,000.00	481,000.00	01-Jun-2007	6.875%	CA - 74.57%	360	01-Mar-2007
6101599 2	360,000.00	360,000.00	01-Jun-2007	8.250%	IL - 80.00%	360	01-Mar-2007
6101678 2	448,000.00	448,000.00	01-Jun-2007	7.125%	VA - 80.00%	360	01-Mar-2007
6111695 2	280,000.00	279,992.42	01-May-2007	7.875%	OR - 80.00%	360	01-Dec-2006
6112644 2	164,000.00	163,076.10	01-Jun-2007	7.875%	FL - 80.00%	360	01-Apr-2007
6112779 2	120,000.00	120,000.00	01-Jun-2007	7.500%	NV - 80.00%	360	01-Mar-2007
6112869 2	672,000.00	672,000.00	01-Jun-2007	8.250%	FL - 80.00%	360	01-Apr-2007
6112902 2	362,400.00	362,400.00	01-May-2007	8.500%	MA - 80.00%	360	01-Mar-2007
6112920 2	438,400.00	438,400.00	01-Jun-2007	8.125%	CA - 79.97%	360	01-Mar-2007
6121512 2	168,000.00	168,000.00	01-May-2007	7.375%	FL - 80.00%	360	01-May-2007
6123131 2	716,000.00	716,000.00	01-Jun-2007	6.875%	CA - 80.00%	360	01-Apr-2007
6123361 2	528,000.00	528,000.00	01-May-2007	6.875%	CA - 80.00%	360	01-Apr-2007
6123615 2	138,750.00	137,766.48	01-Jun-2007	7.875%	NV - 75.00%	360	01-Feb-2007
6123733 2	360,000.00	360,000.00	01-May-2007	7.250%	CO - 80.00%	360	01-Feb-2007
6124927 2	396,000.00	396,000.00	01-May-2007	7.000%	NJ - 80.00%	360	01-May-2007
6124941 2	101,250.00	100,811.43	01-May-2007	8.500%	FL - 75.00%	360	01-May-2007
6124950 2	616,000.00	616,000.00	01-Jun-2007	7.625%	FL - 80.00%	360	01-Jun-2007
6127452 1	466,000.00	466,000.00	01-Jun-2007	7.000%	CT - 79.93%	360	01-May-2007
124128270 2	172,000.00	170,224.88	01-May-2007	8.125%	IL - 80.00%	360	01-Sep-2006
125259163 2	234,400.00	234,400.00	01-Jun-2007	8.500%	CO - 80.00%	360	01-Feb-2007
125315192 2	328,000.00	328,000.00	01-Jun-2007	7.750%	FL - 80.00%	360	01-Feb-2007
125628213 2	172,000.00	172,000.00	01-Jun-2007	7.125%	AZ - 80.00%	360	01-Mar-2007
125645989 2	774,400.00	774,400.00	01-May-2007	7.250%	CA - 80.00%	360	01-Mar-2007
125650766 1	247,920.00	247,920.00	01-May-2007	7.125%	CA - 80.00%	360	01-Mar-2007
125723881 2	233,192.00	233,089.01	01-Jun-2007	8.250%	NV - 80.00%	360	01-Jan-2007
125723882 2	230,392.00	230,368.17	01-Jun-2007	8.250%	NV - 80.00%	360	01-Jan-2007
125823035 2	396,448.00	396,448.00	01-May-2007	6.990%	CA - 70.72%	360	01-Apr-2007
125928547 2	488,000.00	485,250.76	01-May-2007	7.875%	NJ - 80.00%	360	01-Apr-2007
125991469 2	440,000.00	437,329.82	01-Jun-2007	7.500%	FL - 80.00%	360	01-Apr-2007
126047226 2	375,000.00	375,000.00	01-Jun-2007	8.375%	NV - 100.00%	360	01-Feb-2007


TOTAL	12,822,472.00	12,807,321.51

Became Foreclosure Property in a Prior Period:
6123608 2	480,000.00	478,773.76	01-May-2007	8.125%	FL - 80.00%	360	01-Mar-2007
6124952 2	504,744.00	504,744.00	01-May-2007	8.875%	AZ - 80.00%	360	01-May-2007
126135859 2	480,000.00	480,000.00	01-May-2007	7.500%	CA - 80.00%	360	01-May-2007


TOTAL	1,464,744.00	1,463,517.76
TOTAL


Page 16 of 29

IndyMac IMSC Mortgage Loan Trust 2007-AR1

Mortgage Pass-Through Certificates

November 26, 2007 Distribution

TOTAL

14,287,216.00

14,270,839.27

Page 17 of 29

IndyMac IMSC Mortgage Loan Trust 2007-AR1



Mortgage Pass-Through Certificates
Mortgage Pass-Through Certificates
November 26, 2007 Distribution

Prepayment Report

VOLUNTARY PREPAYMENTS
VOLUNTARY PREPAYMENTS

		Group 3	Group 2	Group 1	Total


Current


Number of Paid in Full Loans	1	11	2	14
Number of Repurchased Loans	0	5	0	5
Total Number of Loans Prepaid in Full	1	16	2	19
Curtailments Amount	102,340.67	17,633.17	1,862.89	121,836.73
Paid in Full Balance	242,000.00	2,783,678.51	455,718.16	3,481,396.67
Repurchased Loans Balance	0.00	2,617,974.11	0.00	2,617,974.11
Total Prepayment Amount	344,340.67	5,419,285.79	457,581.05	6,221,207.51
Cumulative


Number of Paid in Full Loans	4	79	4	87
Number of Repurchased Loans	0	6	0	6
Total Number of Loans Prepaid in Full	4	85	4	93
Paid in Full Balance	2,060,992.45	28,806,551.40	1,314,968.16	32,182,512.01
Repurchased Loans Balance	0.00	2,830,724.11	0.00	2,830,724.11
Curtailments Amount	115,434.76	117,224.58	4,611.34	237,270.68
Total Prepayment Amount	2,176,427.21	31,754,500.09	1,319,579.50	35,250,506.80

Page 18 of 29

IndyMac IMSC Mortgage Loan Trust 2007-AR1



Mortgage Pass-Through Certificates
Mortgage Pass-Through Certificates
November 26, 2007 Distribution


VOLUNTARY PREPAYMENTS RATES - Including Liquidated Balances



		Group 3	Group 2	Group 1	Total





SMM	0.60%	0.95%	1.15%	0.93%
3 Months Avg SMM	0.86%	0.87%	0.94%	0.87%
12 Months Avg SMM	0.74%	1.09%	0.66%	1.03%
Avg SMM Since Cut-off	0.74%	1.09%	0.66%	1.03%



CPR	6.94%	10.84%	12.96%	10.64%
3 Months Avg CPR	9.88%	9.97%	10.71%	10.00%
12 Months Avg CPR	8.56%	12.32%	7.61%	11.73%
Avg CPR Since Cut-off	8.56%	12.32%	7.61%	11.73%



PSA	420.52%	632.49%	722.30%	620.92%
3 Months Avg PSA Approximation	678.69%	658.26%	671.79%	660.83%
12 Months Avg PSA Approximation	680.27%	936.42%	545.89%	891.80%
Avg PSA Since Cut-off Approximation	680.27%	936.41%	545.88%	891.80%


(*) SMM, CPR, PSA Figures Include Liquidated Balances

Page 19 of 29

IndyMac IMSC Mortgage Loan Trust 2007-AR1

Mortgage Pass-Through Certificates

November 26, 2007 Distribution

PREPAYMENT CALCULATION METHODOLOGY - Including Liquidated Balances

Single Monthly Mortality (SMM): (Voluntary partial and full prepayments + Repurchases + Liquidated Balances)/(Beg Principal Balance - Sched Principal)

Conditional Prepayment Rate (CPR): 1-((1-SMM)^12)

PSA Standard Prepayment Model: CPR/(0.20%*min(30,WAS))

Average SMM over period between nth month and mth month (AvgSMMn,m): 1 - [(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/(0.20%*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 20 of 29

IndyMac IMSC Mortgage Loan Trust 2007-AR1



Mortgage Pass-Through Certificates
Mortgage Pass-Through Certificates
November 26, 2007 Distribution


VOLUNTARY PREPAYMENTS RATES - Excluding Liquidated Balances



		Group 3	Group 2	Group 1	Total





SMM	0.60%	0.95%	1.15%	0.93%
3 Months Avg SMM	0.86%	0.87%	0.94%	0.87%
12 Months Avg SMM	0.74%	1.09%	0.66%	1.03%
Avg SMM Since Cut-off	0.74%	1.09%	0.66%	1.03%



CPR	6.94%	10.84%	12.96%	10.64%
3 Months Avg CPR	9.88%	9.97%	10.71%	10.00%
12 Months Avg CPR	8.56%	12.32%	7.61%	11.73%
Avg CPR Since Cut-off	8.56%	12.32%	7.61%	11.73%



PSA	420.52%	632.49%	722.30%	620.92%
3 Months Avg PSA Approximation	678.69%	658.26%	671.79%	660.83%
12 Months Avg PSA Approximation	680.27%	936.42%	545.89%	891.80%
Avg PSA Since Cut-off Approximation	680.27%	936.41%	545.88%	891.80%

(*) SMM, CPR, PSA Figures Exclude Liquidated Balances
(*) SMM, CPR, PSA Figures Exclude Liquidated Balances

Page 21 of 29

IndyMac IMSC Mortgage Loan Trust 2007-AR1

Mortgage Pass-Through Certificates

November 26, 2007 Distribution

PREPAYMENT CALCULATION METHODOLOGY - Excluding Liquidated Balances

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/(0.20%*min(30,WAS))

Average SMM over period between nth month and mth month (AvgSMMn,m): 1 - [(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/(0.20%*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 22 of 29

IndyMac IMSC Mortgage Loan Trust 2007-AR1



Mortgage Pass-Through Certificates
Mortgage Pass-Through Certificates
November 26, 2007 Distribution

Prepayment Detail Report

Prepayment Detail Report - Mortgage Loans Prepaid in Full During Current Distribution


Loan Number		Original			Current	State &	Type Prepayment	First


&	Loan	Principal	Prepayment	Prepayment	Note	LTV at	&	Payment

Loan Group	Status	Balance	Amount	Date	Rate	Origination	Original Term	Date

6086840 2		308,750.00	308,750.00	15-Nov-2007	8.438%	IL - 95.00%	Paid Off - 360	01-Jan-2007
6086840 2		308,750.00	308,750.00	15-Nov-2007	8.438%	IL - 95.00%	Paid Off - 360	01-Jan-2007
6086859 2		246,500.00	244,981.76	18-Oct-2007	9.063%	IL - 85.00%	Paid Off - 360	01-Dec-2006
6098988 2		181,144.00	181,144.00	16-Oct-2007	7.500%	UT - 80.00%	Paid Off - 360	01-Mar-2007
6102959 3		242,000.00	242,000.00	18-Oct-2007	6.250%	NV - 74.92%	Paid Off - 360	01-Feb-2007
6112285 1		103,000.00	103,000.00	01-Nov-2007	8.375%	FL - 40.08%	Paid Off - 360	01-Mar-2007
6112640 2		68,800.00	68,426.73	25-Oct-2007	7.375%	TX - 80.00%	Paid Off - 360	01-Apr-2007
6112671 2		228,000.00	226,398.34	09-Nov-2007	6.750%	MN - 80.00%	Paid Off - 360	01-Mar-2007
6113433 2		500,000.00	500,000.00	09-Nov-2007	6.375%	CA - 64.94%	Paid Off - 360	01-Mar-2007
6122986 2		337,000.00	334,977.78	22-Oct-2007	5.375%	CA - 60.18%	Paid Off - 360	01-Apr-2007
125259131 2		252,000.00	252,000.00	16-Oct-2007	7.750%	NV - 80.00%	Paid Off - 360	01-Feb-2007
125336297 1		352,800.00	352,718.16	01-Nov-2007	6.500%	UT - 80.00%	Paid Off - 360	01-Feb-2007
125628198 2		211,000.00	210,999.90	01-Nov-2007	6.875%	VA - 47.42%	Paid Off - 360	01-Mar-2007
125628212 2		380,800.00	380,800.00	17-Oct-2007	7.500%	NV - 80.00%	Paid Off - 360	01-Mar-2007
125991513 2		75,200.00	75,200.00	26-Oct-2007	8.250%	AZ - 80.00%	Paid Off - 360	01-Apr-2007
6122984 2		516,000.00	516,000.00	31-Oct-2007	6.250%	CA - 80.00%	Repur/Subs - 360	01-Apr-2007
6123287 2		576,000.00	576,000.00	31-Oct-2007	7.625%	CA - 80.00%	Repur/Subs - 360	01-Apr-2007
6125019 2		452,000.00	452,000.00	31-Oct-2007	6.875%	CA - 80.00%	Repur/Subs - 360	01-May-2007
6125177 2		641,000.00	640,474.11	31-Oct-2007	7.750%	IL - 76.12%	Repur/Subs - 360	01-May-2007
6125213 2		433,500.00	433,500.00	31-Oct-2007	7.375%	CA - 85.00%	Repur/Subs - 360	01-May-2007


TOTAL	6,105,494.00	6,099,370.78

Page 23 of 29

IndyMac IMSC Mortgage Loan Trust 2007-AR1



Mortgage Pass-Through Certificates
Mortgage Pass-Through Certificates
November 26, 2007 Distribution

Realized Loss Report

COLLATERAL REALIZED LOSSES


		Group 3	Group 2	Group 1	Total


Current





	Subsequent Recoveries					0.00

	Number of Loans Liquidated		0	0	0	0
	Collateral Principal Realized Loss/(Gain) Amount		0.00	0.00	0.00	0.00
	Collateral Interest Realized Loss/(Gain) Amount		0.00	0.00	0.00	0.00
Net Liquidation Proceeds		0.00	0.00	0.00	0.00
Cumulative




	Number of Loans Liquidated		0	0	0	0

	Collateral Realized Loss/(Gain) Amount		0.00	0.00	0.00	0.00
	Net Liquidation Proceeds		0.00	0.00	0.00	0.00
Cumulative Subsequent Recoveries					0.00



	Special Hazard Loss Coverage Amt					6,992,172.00
	Fraud Loss Coverage Amt					13,922,550.00
	Bankruptcy Loss Coverage Amt					310,337.00

Page 24 of 29

IndyMac IMSC Mortgage Loan Trust 2007-AR1



Mortgage Pass-Through Certificates
Mortgage Pass-Through Certificates
November 26, 2007 Distribution


DEFAULT SPEEDS
DEFAULT SPEEDS
	Group 3	Group 2	Group 1	Total




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


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


SDA	0.00%	0.00%	0.00%	0.00%
3 Months Avg SDA Approximation	0.00%	0.00%	0.00%	0.00%
12 Months Avg SDA Approximation	0.00%	0.00%	0.00%	0.00%
Avg SDA Since Cut-off Approximation	0.00%	0.00%	0.00%	0.00%


Principal Only Loss Severity Approx for Current Period	0.00%	0.00%	0.00%	0.00%
3 Months Avg Loss Severity Approximation	0.00%	0.00%	0.00%	0.00%
12 Months Avg Loss Severity Approximation	0.00%	0.00%	0.00%	0.00%
Avg Loss Severity Approximation Since Cut-Off	0.00%	0.00%	0.00%	0.00%


Principal & Interest Loss Severity Approx for Current Period	0.00%	0.00%	0.00%	0.00%
3 Months Avg Loss Severity Approximation	0.00%	0.00%	0.00%	0.00%
12 Months Avg Loss Severity Approximation	0.00%	0.00%	0.00%	0.00%
Avg Loss Severity Approximation Since Cut-Off	0.00%	0.00%	0.00%	0.00%

Page 25 of 29

IndyMac IMSC Mortgage Loan Trust 2007-AR1

Mortgage Pass-Through Certificates

November 26, 2007 Distribution

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)

Principal Only Loss Severity Approximation for current period:

Sum(Principal Realized Loss Amount)/sum(Beg Principal Balance of Liquidated Loans)

Principal & Interest Loss Severity Approximation for current period:

Sum(Principal & Interest Realized Loss Amount)/sum(Beg Principal Balance of Liquidated Loans)

Average Loss Severity Approximation over period between nth month and mth month:

Sum(Realized Loss Amount)/sum(Beg Principal Balance of Liquidated Loans for months in the period n,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.

All Realized Losses in excess of Principal Balance are treated as Interest Realized Losses.

Page 26 of 29

IndyMac IMSC Mortgage Loan Trust 2007-AR1

Mortgage Pass-Through Certificates

November 26, 2007 Distribution

Realized Loss Detail Report

Loan Number

Current

State &

Prior

Realized

Cumulative

Loan

Note

LTV at

Original

Principal

Loss/(Gain)

Realized

Loan Group

Status

Rate

Origination

Term

Balance

Revision

Loss/(Gain)

TOTAL

Page 27 of 29

IndyMac IMSC Mortgage Loan Trust 2007-AR1

Mortgage Pass-Through Certificates

November 26, 2007 Distribution

Triggers and Adj. Cert. Report

TRIGGER EVENTS

Group 3

Group 2

Group 1

Total

Has Optional Termination Date Reached ?

Has Sr. Credit Supp. Depletion Date Occured ?

Has Special Haz. Cov. Term Date Occured ?

Has Fraud Loss Coverage Term Date Occured ?

Has BK Loss Cov. Term Date Occured ?

Does an Event of Default Exist?

Senior Stepdown Date has occurred?

Sr.Stepdown Cond Satisfied?(1=Yes or 2=Yes)

1.Delinquency Trigger

Does Delinquency Trigger Event Exist (a > 50% of b)

(a) Rolling Six Month 60+ Delq Balance

20,464,498.53

(b) Aggregate Balance of Subordinate Certificates

67,557,584.37

2.Cumulative Loss Trigger

Does a Loss Trigger Event Exist (a > b)

(a) Cumulative Realized Loss

0.00

(b) Cumulative Loss Threshold (i)*(ii)

67,872,417.00

(i) Threshold Percentage

100.0000%

(ii) Cutoff Date Subordinate Principal Balance

67,872,417.00

ADJUSTABLE RATE CERTIFICATE INFORMATION

SPACE INTENTIONALLY LEFT BLANK

ADDITIONAL INFORMATION

Group 3

Group 2

Group 1

Total

Senior Percentage

89.939666%

89.802936%

90.039139%

Subordinate Percentage

10.060334%

10.197064%

9.960861%

Senior Prepayment Percentage

100.000000%

Subordinate Prepayment Percentage

0.000000%

Subordinate Pass Through Rate

6.528559%

Page 28 of 29

IndyMac IMSC Mortgage Loan Trust 2007-AR1



Mortgage Pass-Through Certificates
Mortgage Pass-Through Certificates
November 26, 2007 Distribution

Other Related Information
ADDITIONAL INFORMATION
ADDITIONAL INFORMATION
	Group 3	Group 2	Group 1	Total
Current Scheduled Payments	321,416.80	3,339,818.28	216,216.87	3,877,451.96
Current Scheduled Payments 1 Month Prior	326,316.98	3,375,940.57	216,220.29	3,918,477.85
Current Scheduled Payments 2 Month Prior	328,480.73	3,412,952.62	220,069.46	3,961,502.80
Current Scheduled Payments 3 Month Prior	332,647.43	3,464,263.55	220,984.47	4,017,895.45
Current Scheduled Payments 4 Month Prior	332,729.35	3,525,436.60	221,024.63	4,079,190.58
Current Scheduled Payments 5 Month Prior	0.00	0.00	0.00	0.00
Current Scheduled Payments 6 Month Prior	0.00	0.00	0.00	0.00
Current Scheduled Payments 7 Month Prior	0.00	0.00	0.00	0.00
Current Scheduled Payments 8 Month Prior	0.00	0.00	0.00	0.00
Current Scheduled Payments 9 Month Prior	0.00	0.00	0.00	0.00
Current Scheduled Payments 10 Month Prior	0.00	0.00	0.00	0.00
Current Scheduled Payments 11 Month Prior	0.00	0.00	0.00	0.00


Sched. Payments for 60+Day Delinquent Loans	15,609.94	288,856.37	10,164.33	314,630.64
Sched. Pmts - 60+Day Delinquent Loans, 1 Month Prior	7,548.60	215,558.38	9,040.96	232,147.95
Sched. Pmts - 60+Day Delinquent Loans, 2 Month Prior	3,741.40	141,587.12	4,190.36	149,518.87
Sched. Pmts - 60+Day Delinquent Loans, 3 Month Prior	2,261.77	81,354.42	1,472.03	85,088.22
Sched. Pmts - 60+Day Delinquent Loans, 4 Month Prior	0.00	0.00	0.00	0.00
Sched. Pmts - 60+Day Delinquent Loans, 5 Month Prior	0.00	0.00	0.00	0.00
Sched. Pmts - 60+Day Delinquent Loans, 6 Month Prior	0.00	0.00	0.00	0.00
Sched. Pmts - 60+Day Delinquent Loans, 7 Month Prior	0.00	0.00	0.00	0.00
Sched. Pmts - 60+Day Delinquent Loans, 8 Month Prior	0.00	0.00	0.00	0.00
Sched. Pmts - 60+Day Delinquent Loans, 9 Month Prior	0.00	0.00	0.00	0.00
Sched. Pmts - 60+Day Delinquent Loans, 10 Month Prior	0.00	0.00	0.00	0.00
Sched. Pmts - 60+Day Delinquent Loans, 11 Month Prior	0.00	0.00	0.00	0.00



Class B-1 Writedown Amount				0.00
Class B-2 Writedown Amount				0.00
Class B-3 Writedown Amount				0.00
Class B-4 Writedown Amount				0.00
Class B-5 Writedown Amount				0.00
Class B-6 Writedown Amount				0.00





Page 29 of 29

IndyMac IMSC Mortgage Loan Trust 2007-AR1 10-D