Most NFIP policies have a 30-day waiting period before coverage takes effect. The waiting period generally starts when your application and full premium are received, so it helps to arrange coverage well before a storm appears in the forecast.
Some situations have a shorter wait:
Mortgage Closings: If flood insurance is required in connection with making, increasing, extending or renewing a mortgage loan, there is generally no waiting period. Coverage can take effect at closing when the application and premium are submitted at or before closing.
Newly Mapped High-Risk Zones: If a map revision newly places your property in a high-risk flood zone, NFIP coverage bought within 13 months of the map revision generally has a one-day waiting period.
Private Flood Insurance: Private carriers set their own waiting periods, and some are shorter than 30 days. Private carriers may also stop issuing new policies or coverage increases when a tropical storm threatens the region.