Federal Code and Regulations typically require that Proofs of Loss for National Flood Insurance claims be filed within 60 days following the loss.  They have to be done completely and on time. The only exception is a written waiver from the Administrator of the National Flood Insurance Program. 

Please find the written extension here

Our offices had numerous phone calls regarding the written extension. Everybody said they heard of one, but finding it proved to be difficult.  I called a National Flood Official that I had litigated with following Hurricane Opal, and he guided me to a rather arcane Internet address that had the written 120 day extension.  The Federal deadline should be longer. Notice of the loss should be prompt, but the Proof requirements should be at least 180 days. Currently, those provisions can act as a bar to recovery to otherwise legitimate claims. We intend to lobby Congress for this extended period.