NFIP Underwater Properties Act This bill requires that the premium rate for flood insurance provided through the National Flood Insurance Program (NFIP) for structures that have incurred repetitive flood-related damage 1) be based on sound actuarial principles, and 2) not be subject to any rate caps if the structure is located in a special flood hazard area. Under current law, certain types of property are not charged actuarial rates for NFIP coverage.