The Renewable Fuel Standard (RFS) requires U.S. transportation fuel to include a minimum volume of renewable fuel each year. The RFS—established by the Energy Policy Act of 2005 (EPAct05; P.L. 109-58) and expanded in 2007 by the Energy Independence and Security Act (EISA; P.L. 110-140)—began with requiring 4 billion gallons of renewable fuel in 2006 and gradually increasing that requirement until it reached 36 billion gallons in 2022. However, for a variety of reasons, the statutory volume requirement for total renewable fuel—which may include both conventional biofuel and advanced biofuel—was not met from 2014 to 2022. As of 2023, the U.S. Environmental Protection Agency (EPA) has the authority to determine annual volume obligations. EPA administers the RFS and is responsible for several related tasks. Using the statutory criteria, EPA evaluates which renewable fuels are eligible for the RFS program. EPA also monitors compliance with the RFS requirements using a system of tradable credits referred to as renewable identification numbers (RINs). From the program’s inception through 2022, EPA established the amount of total renewable fuel that refiners and importers had to account for in the coming year based on statutory targets, fuel supply, and other conditions. EPA exercised statutory waiver authorities to reduce volumes when necessary. For the final nine years of the program’s statutory annual requirements (i.e., the latter half of 2014 through 2022), EPA set the total renewable fuel volume below the statutory amount—using its waiver authorities—mainly due to underproduction of advanced biofuel. The RFS began a new phase in 2023, when EPA began to have statutory authority and an obligation to determine the annual volume requirements. Under the current statutory authority, EPA is to determine the volume requirements, in coordination with the Secretaries of Energy and Agriculture, based on a review of program implementation for prior years and an analysis of various criteria (e.g., the impact of renewable fuels on the energy security of the United States). EPA has used such authority previously. EPA determined the volume amounts for biomass-based diesel from 2013 onward, via the rulemaking process, after the annual statutory targets for biomass-based diesel ended in 2012. EPA is issuing “set rules” in accordance with what the agency refers to as the “set authority,” the authority for the agency to set applicable volumes for years not specified in the statutory tables. The Set 1 Rule covers the applicable volume requirements and percentage standards for 2023 through 2025, along with regulatory changes. In March 2026, EPA released the Set 2 Rule, which covers the applicable volume requirements and percentage standards for 2026 and 2027. As part of the Set 2 Rule, EPA also partially waived the 2025 cellulosic biofuel volume requirement; removed renewable electricity as a qualifying renewable fuel for the program; required a 70% partial reallocation of the 2023-2025 exempted renewable volume obligations from small refinery exemptions to the 2026 and 2027 compliance years; and finalized various regulatory changes (e.g., set a new equivalence value for renewable diesel). Though included in its June 2025 Set 2 proposed rule, EPA decided not to finalize at this time its import RIN reduction (IRR) policy proposal that would reduce the number of compliance credits (i.e., RINs) generated for imported renewable fuel and renewable fuel produced from foreign feedstocks. EPA reports in the Set 2 rule that they believe this IRR policy “is appropriate and would better align the RFS program with the statutory goals for the program.” EPA plans to issue provisions related to this matter that are expected to “take effect at the beginning of the 2028 compliance year or sometime shortly thereafter.” Congress has expressed interest in various facets of the RFS. EPA gives attention to some of these issues in the 2026 and 2027 RFS final rule (e.g., treatment of renewable electricity and small refinery exemption reallocation). Recent legislative activity (e.g., an amendment to the 2026 House farm bill that “would make targeted reforms to the small refinery exemption program under the Renewable Fuel Standard”), presidential actions (e.g., executive orders), and legal challenges may also be of interest to Congress in its ongoing oversight of the RFS.
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