How to show when loan was paid off

First time posting but have been a reader for over 10 years. I have a need to show when a loan was paid off regardless of the rolling balance from refinancing/taking out additional loans. In the other column I want to show pay down balance like 950.00, 850.00, 800.00, 720.00 until I get to zero balance for the LOAN_ID 215, After which I want to then apply remaining payments to LOAN_ID 431 I'm using SQL Server 2005/2008. Here is my table: CUST_ID LOAN_ID PMNT_ID PMNT_AMT PMNT_DT LOAN_AMT LOAN_FUND_DT PMNT_RUN_TOT 1155 215 100 100.00 02/15/2015 1050.00 01/15/2015 100.00 1155 215 101 100.00 03/15/2015 1050.00 01/15/2015 200.00 1155 215 102 50.00 03/31/2015 1050.00 01/15/2015 250.00 1155 215 103 90.00 04/15/2015 1050.00 01/15/2015 340.00 1155 215 104 150.00 04/25/2015 1050.00 01/15/2015 490.00 1155 215 105 120.00 05/15/2015 1050.00 01/15/2015 610.00 1155 431 106 100.00 05/25/2015 2100.00 05/20/2015 710.00 1155 431 107 100.00 06/15/2015 2100.00 05/20/2015 810.00 1155 431 108 100.00 06/30/2015 2100.00 05/20/2015 910.00 1155 431 109 100.00 07/15/2015 2100.00 05/20/2015 1010.00 1155 431 110 100.00 08/15/2015 2100.00 05/20/2015 1110.00 1155 431 111 100.00 09/15/2015 2100.00 05/20/2015 1210.00 1155 431 112 100.00 09/30/2015 2100.00 05/20/2015 1310.00 1155 431 113 100.00 10/15/2015 2100.00 05/20/2015 1410.00 The first loan was paid off with PMNT_ID 110 and 60.00 was rolled over into the pay down of 2100.00 loan. Here is how the output should look cust_id|loan_id | loan_amount | Loan Bal |paid_off_date ---------------------------------------------------- 1155 | 215| 1050 | 0.00 |2015-08-15 1155 | 431| 2100 | 1800.00 |null Any suggestions on how to show this in another column called "Bal_Pay_Down" ?