I found a great resource for looking up (very) detailed info on loan conditions and guidelines. The document is available on the Fannie Mae website, and there's a direct link to the doc below.
Note this is a guide from Fannie Mae, and specifically applies to loans that are sold to Fannie Mae to repackage into an investment product (a "conforming loan") - it is not an "end-all, be-all" bible of all mortgage requirements ever, and may not even apply to your situation. BUT it might give you a good idea what the answer to your question is...
Before you jump in, some comments:
1) The document is long, well over 1000 pages. You'd do well to bookmark it and get good at searching Acrobat files.
2) The section to start with is probably B3 (Underwriting Borrowers). This section covers basically all of the guidelines for borrower qualification, and weighs ~240 pages. That said, I've spent two hours on this and feel like I've just scratched the surface...
February 2012 version:
https://www.efanniemae.com/sf/guides/ssg/sg/pdf/sel022812.pdf
I hope some forum members more knowledgeable than I can chime in with their thought and experience with this document. Happy reading!
