A bit of a longer read from Kiva here.

http://www.kiva.org/updates/kiva/2012/08/13/qa-expiring-loans-credit-limits-and-the-evolution-of-kiv...

Just one snippet -

"As we explained in #9, Field Partners bear the brunt of expirations. If a loan is pre-disbursed, the Field Partner has to fund it out of its own reserves. The impact is minimal if the borrower pays the loan back in full. But, if the borrower doesn’t pay back the loan and the loan has expired on Kiva, the Field Partner must cover the loss out of its own pocket. This may be a rare occurrence, but it can have a negative impact on a partner depending on its size and financial stability."