Renewable Fuel Standard Flexibility Act - Amends the Clean Air Act to require the Administrator of the Environmental Protection Agency (EPA): (1) by November 30 each year, to determine and publish the estimated U.S. corn stocks-to-use ratio for the applicable crop year; and (2) to waive the renewable fuel program's requirements for the next calendar year by reducing the national quantity of renewable fuel otherwise required by specified amounts based on the ratio determined.
Prohibits: (1) waivers granted under this Act from affecting the volume of advanced biofuel under such program, or (2) the Administrator from allowing any volume of conventional biofuel to be used to satisfy the requirement for advanced biofuel.