State Flood Mitigation Revolving Fund Act of 2018 This bill amends the National Flood Insurance Act of 1968 to permit the Federal Emergency Management Agency (FEMA) to provide capitalization grants to states to establish revolving funds to address flood risks. Revolving funds may be used to provide: (1) financial assistance to participants in the National Flood Insurance Program, including homeowners, businesses, nonprofit organizations, and local governments; or (2) support for leveraged loans or state bonds. Financial assistance may be used for elevation projects, flood-proofing activities, relocation or removal of buildings, environmental restoration, acquiring property, obtaining protective easements, and other activities identified by FEMA. States must annually submit to FEMA a plan that identifies the intended uses of the state loan fund. States may provide additional subsidies to low-income homeowners and recipients of financial assistance in low-income areas.