Debate Intensifies Over California’s Proposed SAF Tax Credit and Its Supply Chain Impact
California’s push to accelerate sustainable aviation fuel (SAF) production is facing growing scrutiny, as policymakers, analysts, and industry stakeholders clash over the costs, benefits, and unintended consequences of a proposed tax credit.
At the center of the debate is a trailer bill introduced by Governor Gavin Newsom, designed to stimulate SAF production through a targeted fiscal incentive. While supporters see it as a necessary step toward decarbonizing aviation, critics argue it could strain public finances, distort fuel markets, and deliver limited environmental benefits.
What the Proposal Includes
First unveiled in January 2026, the proposal offers SAF producers a base $1 per gallon tax credit under California’s Diesel Fuel Tax Law. The incentive would apply to fuel produced and sold between 2026 and 2035, with eligibility tied to lifecycle emissions performance. Producers could earn additional credits, up to $2 per gallon total, by achieving deeper carbon intensity reductions beyond a 50% threshold compared to conventional jet fuel.
The California Air Resources Board (CARB) would be responsible for certifying credits based on prior-year sales. Any unused credits could be carried forward for up to five years.
Lawmakers and Analysts Raise Concerns
During an April 9 Senate subcommittee hearing, skepticism emerged around both the cost-effectiveness and policy trade-offs of the proposal. Analysts from California’s Legislative Analyst’s Office argued the measure may not deliver meaningful emissions reductions. Aviation accounts for only about 1% of the state’s greenhouse gas emissions, raising questions about whether the incentive targets the right sector.
Others warned the policy could significantly reduce diesel excise tax revenues — funds typically allocated to road maintenance and infrastructure. Some projections suggest a potential decline of 20% to 75% in tax receipts, which could ultimately impact public budgets and consumer fuel prices. There were also concerns about market distortion, particularly the possibility that incentives could shift production away from renewable diesel toward SAF, increasing compliance costs under California’s Low Carbon Fuel Standard.
Industry Pushback—and Support
Not all stakeholders agree with the pessimistic outlook.
Officials from CARB highlighted significant growth in waste-based feedstocks, noting that supply has nearly tripled in the past five years. This trend, they argue, demonstrates the market’s ability to scale in response to policy signals.
Similarly, representatives from California’s Department of Finance pushed back on concerns about fuel price increases, suggesting those outcomes depend on assumptions about constrained feedstock supply that may not hold true.
Industry voices are also advocating for modifications rather than rejection of the policy. Some stakeholders argue the credit should be expanded to include independent SAF producers, not just companies with diesel tax liability, and aligned with federal and international frameworks such as Section 45Z and CORSIA.
Supply Chain Realities and Market Dynamics
A key tension in the debate is whether the SAF incentive could disrupt existing renewable fuel markets.
Some experts argue that fears of supply constraints are overstated. With U.S. renewable diesel production currently operating below full capacity, additional demand could be met through expanded logistics rather than price increases.
Others go further, suggesting that increased SAF production could actually reduce gasoline prices. By displacing petroleum-based jet fuel demand, refiners may be able to rebalance output toward gasoline, improving overall yield efficiency.
The Refining Question
Lawmakers also questioned whether the policy implicitly favors specific facilities or companies.
Attention has turned to Phillips 66 and its Rodeo refinery — one of the few U.S. facilities capable of producing SAF at scale. The site, which transitioned to renewable fuel production in 2024, currently produces approximately 150 million gallons of SAF annually.
Some legislators expressed concern about whether the credit is effectively designed to support such facilities, rather than fostering a broader, more competitive SAF market.
Airlines and Long-Term Demand
Despite policy uncertainty, airlines continue to signal strong interest in SAF as a decarbonization tool. Delta Air Lines, for example, has committed to sourcing 10% SAF by 2030 and increased its usage significantly over the past year. However, the company, and the broader aviation sector, acknowledges that technology and supply have not scaled quickly enough to meet long-term climate goals.
What Happens Next
The future of the SAF tax credit remains uncertain. Governor Newsom is expected to release a revised budget proposal in mid-May, following negotiations with state lawmakers. A final budget must be approved by June 15, with potential last-minute amendments extending into early July.
California’s SAF tax credit proposal highlights a broader challenge facing energy transition policies: balancing climate ambition, economic competitiveness, and consumer affordability. Whether the measure moves forward in its current form, or is significantly revised, will depend on how policymakers navigate competing priorities across emissions reduction, infrastructure funding, and market stability.
What is clear is that SAF will remain a critical, and contested, piece of the decarbonization puzzle in the years ahead.