From the Federal Reserve Exam Manual:
Reliance on Prior Determination
When determining whether flood insurance is required, an institution may consider the conclusions from a previous flood hazard area determination if both of the following conditions are met:
• The previous determination is not more than seven years old.
• The basis for that determination was recorded on the SFHDF mandated by the Reform Act.
An institution may not rely on a previous determination in two situations:
• If FEMA’s map revisions or updates show that the security property is now located in an SFHA
• If the lender contacts FEMA and learns that map revisions or updates affecting the security property have been made since the date of the previous determination
An institution may not rely on a previous determination set forth on an SFHDF when it makes a loan—only when it increases, extends, renews, or purchases a loan. Subsequent transactions by the same institution with respect to the same property, such as assumptions, refinancings, and second-lien loans, are to be treated as loan renewals. In those limited circumstances, a new determination is not required, assuming that the other requirements are met.
http://www.federalreserve.gov/boarddocs/supmanual/cch/flood.pdfHowever, you are NOT required to pull flood to monitor your portfolio... so if the loan is out there for 15 years, you can rely on the LOL. But, if you increase, renew, or extend that loan, then the above rules apply.