What Is the Issue Date Unpaid Principal Balance?

The Issue Date Unpaid Principal Balance is the principal balance of each mortgage in an MBS pool after crediting the principal portion of any monthly payments due on or before the issue date for the related securities (whether or not it was actually collected) and after crediting any unscheduled partial payment on or before the issue date (as long as it was not accompanied by payment of an interest amount that represented scheduled interest due for the month after the payment was made). 

All borrower-remitted curtailments received by the lender prior to delivery of a loan must be applied prior to delivery and may not be held by the lender until after the MBS Issuance.

What this means: The Issue Date UPB of the loan is the balance of the loan as of the issue month, regardless of whether the payment has been made by the borrower, including all curtailments. The Current Balance is used to calculate the Issue Date UPB. 

General Rules:

• If the loan Last Paid Installment (LPI) Date = Pool Issue Date: The Issue UPB and Current Balance must be equal.
• If the loan LPI Date < Pool Issue Date: Amortize Current Balance for 1 Additional Month
• If the loan LPI Date > Pool Issue Date: Reverse Amortize the Current Balance by the number of months greater than the Pool Issue Date.
• For a new loan, where a payment has not been made, the LPI Date must be one month before the First Payment Date.