House bill could reshape U.S. biofuels tax policy, 45Z eligibility

The House on May 22 passed H.R. 1 by 215-214, keeping 45Z in play and resetting the tax calculus for ethanol, biodiesel, renewable diesel and SAF. President Donald Trump signed the revised bill on July 4, and Congress.gov identifies it as the One Big Beautiful Bill Act in the 119th Congress. The law extended Section 45Z to December 31, 2029, and the credit now turns on carbon intensity scoring, feedstock origin and plant-level decarbonization choices.

What the law changed

The clean-fuel production credit was created under the Inflation Reduction Act, then sustained and modified in the One Big Beautiful Bill Act. Treasury’s framework applies to eligible fuels produced after December 31, 2024 and sold before January 1, 2030, with a base value of $0.20 per gallon for non-aviation fuel and $0.35 per gallon for SAF. That puts a dollar figure on carbon performance, not just on gallons, and it makes the 45ZCF-GREET model central to project economics.

Corn ethanol now lives or dies on carbon intensity

For corn ethanol plants, the question is no longer only whether the gallon qualifies. It is whether a plant can lower lifecycle emissions enough to secure more value under 45Z, and the most obvious levers are carbon capture and sequestration, renewable electricity procurement and renewable natural gas used as process heat. Those investments have moved from optional upgrades to commercial differentiators because Treasury’s clean-fuel credit is tied to carbon intensity scoring.

The policy shift elevates domestic feedstocks and rewards lower-carbon producers that can document the right inputs and operating changes. That is a better fit for plants that can bolt on CCS, switch boilers to RNG or sign renewable power contracts than for facilities still running a conventional energy stack. In practical terms, the lowest-CI corn ethanol plants are the ones most likely to see 45Z as a durable margin enhancer, especially if they can also serve future alcohol-to-jet demand.

The Renewable Fuels Association urged Treasury on May 27, 2026 to finalize clear, stable and practical regulations and to release an updated 45ZCF-GREET model. Much of the credit’s value still depends on the emissions tables and verification rules, not just on the statute.

SAF gets a different signal

SAF is the pathway most sensitive to any improvement in ethanol’s carbon score. Lower carbon intensity scores for ethanol could make alcohol-to-jet routes more competitive. The SAF credit sits at $0.35 per gallon, above the $0.20 rate for non-aviation fuel. If ethanol can clear a stronger CI score through CCS, clean power or RNG, it becomes a better feedstock for alcohol-to-jet conversion and a more credible bridge between grain-based fuel and aviation demand.

That is where the House language and the later Senate revisions split the market’s expectations. Clean Air Task Force said H.R. 1 expands 45Z for conventional biofuels while cutting the sustainable aviation fuel tax credit. Producers that can pivot toward SAF-linked volumes may prefer a policy regime that preserves the higher aviation rate and keeps CI scoring generous; producers tied to conventional blending will push for a broader 45Z runway and more permissive emissions accounting.

Domestic feedstocks gained leverage, foreign inputs lost some value

The clearest winner in the policy shift is the domestic feedstock chain. On June 16, Senate Republicans proposed a 20% haircut to the credit for biofuels made from feedstocks produced outside the United States. That would hit imported canola and used cooking oil used in some renewable diesel and SAF production, while steering more value toward U.S.-grown corn, soy oil and other domestic inputs.

That foreign-feedstock language quickly drew farm-state scrutiny. Soybean growers raised concern on June 18, while the American Farm Bureau Federation and other ag groups have treated 45Z as a demand lever for U.S. crops and oilseeds. The more the credit rewards domestic feedstocks, the more it favors plants that can document U.S. sourcing and the less room there is for imported low-cost inputs to capture tax value.

Implementation still sets the floor

Treasury and the IRS have not finished turning the statute into working rules. The agencies issued a proposed rule for Section 45Z on February 4, 2026, and industry responses through April 6 focused on how emissions rates, verification and registration would be handled. The Renewable Fuels Association and Clean Fuels Alliance America both pushed for faster, clearer guidance, because without an accepted 45ZCF-GREET framework the market cannot price credits cleanly.