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F-3-09, Acronyms and Glossary of Defined Terms: I (08/17/2016)


Independent Dispute Resolution

impasse process

An option available to a seller/servicer or other responsible party for challenging a demand for a servicing remedy after the conclusion of the appeal process.

imputed interest

The interest that Fannie Mae assesses on a loan after it has been foreclosed or liquidated in order to compensate it for the loss of the use of the funds advanced.

inactive document custodian

An entity that has not certified MBS or portfolio mortgage loans for Fannie Mae in the previous calendar year but is holding mortgage loans in custody for Fannie Mae.

independent dispute resolution process

The process for resolving loan-level disputes involving a breach of the Lender Contract. Also referred to as “IDR.”

institutional lender

A financial institution that invests in mortgage loans and keeps them in its own portfolio.

interest accrual rate

The percentage rate at which interest accrues on the mortgage. In most cases, it is also the rate used to calculate the monthly payments, although it is not used for ARM loans with payment change limitations.

interest bearing UPB

The portion of the UPB on which interest accrues.

interest rate differential

See yield differential adjustment. 


Internal Revenue Service

issue date

The first day of the month in which securities backed by an MBS pool are issued.

issue date principal balance

The principal balance of each mortgage loan 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 or other recovery of principal received 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).