The "Keeping Homeownership Costs Down Act" amends the National Flood Insurance Act of 1968 to prohibit the deferral of issuing certain flood map revisions. Specifically, it prevents the Administrator from delaying the issuance of letters of map revision (LOMR) or conditional letters of map revision (CLOMR) when these revisions are based on the placement of fill material. This prohibition is not permanent; it includes a repeal clause . The amendment will be repealed once the Administrator of the Federal Emergency Management Agency (FEMA) fully implements the requirements outlined in specific biological opinions from the Fish and Wildlife Service and the National Oceanic and Atmospheric Administration, which are related to the Endangered Species Act and concern these types of flood map revisions.