SAF Mandates Explained: The Best 2026 Guide to ReFuelEU and UK Rules

Updated September 18, 2026 · 12 min read

A SAF mandate is a legal obligation on jet fuel suppliers to blend a minimum share of sustainable aviation fuel into the fuel they sell. In 2025 the era of voluntary pledges ended: the EU’s ReFuelEU Aviation regulation and the UK’s SAF Mandate both came into force, turning SAF from a marketing story into a compliance requirement with severe financial penalties. This guide explains how each SAF mandate works, the exact blending percentages year by year, what non-compliance costs, and what it all means for airlines, fuel producers and ticket prices.

What is a SAF mandate and why do they exist?

Sustainable aviation fuel is chemically close enough to fossil kerosene to power today’s aircraft with no modification, and it can cut lifecycle CO₂ emissions by 70–80% or more depending on the pathway. The problem has always been price: SAF costs roughly two to five times more than conventional jet fuel, so no airline buys it voluntarily at scale. In 2025, SAF still made up well under 1% of global jet fuel demand.

A SAF mandate breaks that deadlock by removing the choice. Instead of subsidising demand, the EU and UK simply require fuel suppliers to blend rising percentages of SAF — and let the extra cost flow through the fuel price to airlines and, ultimately, passengers. It is the same regulatory logic that built the wind and solar industries: guarantee demand, and investment in production capacity follows. For the underlying technology and feedstocks, start with our full explainer on sustainable aviation fuel.

Mandates also work alongside — not instead of — carbon pricing. Airlines flying internationally still face offsetting obligations under ICAO’s scheme, which we cover in our guide to CORSIA, and intra-European flights pay for allowances under the EU ETS.

ReFuelEU Aviation: the EU SAF mandate

ReFuelEU Aviation (Regulation 2023/2405) is the EU’s flagship aviation decarbonisation law. Since 1 January 2025, every supplier delivering jet fuel to EU airports must ensure a minimum SAF share, and the obligation ratchets up every five years until 2050.

Three design choices define the EU approach. First, the obligation sits on fuel suppliers, not airlines — simpler to enforce at a few dozen supply points than across hundreds of carriers. Second, crop-based biofuels do not count: the EU excluded food and feed crops to avoid repeating the deforestation controversies of road biodiesel, which is why compliance fuel today is overwhelmingly made from used cooking oil and animal fats. Third, an anti-tankering rule requires airlines to uplift at least 90% of the fuel they need at each EU airport, so carriers cannot dodge the mandate by filling their tanks with cheap fossil fuel abroad.

The e-SAF sub-target deserves special attention. Synthetic kerosene made from green hydrogen and captured CO₂ is today the most expensive fuel on Earth — the EASA reference price used for 2025 penalties works out around €14,000 per tonne, versus roughly €2,700 for bio-based SAF. The sub-mandate exists precisely because e-fuels are the only pathway that scales without feedstock limits, a theme we explore in our comparison of electric vs hydrogen aircraft.

The UK SAF Mandate

The UK left the EU scheme behind and built its own version, in force since 1 January 2025 under the Energy Act. It covers jet fuel supplied for flights departing UK airports and is administered through a tradeable certificate system similar to the existing renewable fuel obligation for road transport.

The UK schedule is front-loaded: 3.6% in 2026 is nearly double the EU requirement for the same year, and 10% by 2030 beats the EU’s 6%. But the UK tops out at 22% in 2040, while the EU keeps climbing to 70% by 2050 — a philosophical difference about how far biofuel and e-fuel supply can realistically stretch.

Two UK-specific mechanisms matter. The HEFA cap progressively limits fuels made from used cooking oil and animal fats, forcing the market toward advanced pathways (municipal waste, forestry residues, e-fuels) before the cheap feedstocks run out. And a revenue certainty mechanism — a contracts-for-difference style price guarantee for UK SAF plants — is being introduced to get domestic production built, because today almost all mandate-compliant fuel is imported.

What non-compliance actually costs

Both regimes back their percentages with financial pain, but they structure it differently.

Enforcement is already being tested. In June 2026 the European Commission opened infringement proceedings against 13 member states that had failed to put their penalty regimes into national law by the December 2024 deadline — a reminder that an EU regulation is only as strong as national enforcement behind it.

For airlines, mandate costs arrive through the fuel bill rather than as a direct obligation, joining the carbon costs they already carry. How those layers stack up against a flight’s true climate impact — including the contrail warming that no fuel mandate addresses — is covered in our guide to aviation non-CO2 effects.

Can supply keep up? The market reality

Mandates guarantee demand; they cannot conjure supply. Global SAF production roughly doubled in 2024 to about one million tonnes and kept growing through 2025 — yet that is still around 0.5–1% of world jet fuel demand of some 300 million tonnes. The mandates were sized with this in mind: 2% of EU plus UK demand is a stretch, not an impossibility, for the current wave of HEFA refineries.

The real crunch comes in two steps. Around 2030, the EU jump to 6% with a 1.2% e-SAF slice collides with the fact that barely a handful of commercial e-kerosene plants exist anywhere. Several announced European e-fuel projects have been delayed or cancelled waiting for firm offtake contracts. And through the 2030s, waste-oil feedstocks plateau — there is only so much used cooking oil in the world, and road transport, shipping and chemicals all compete for it. The UK’s declining HEFA cap is an explicit bet that advanced pathways must take over.

Price forecasts reflect the squeeze: analysts put blended SAF at roughly $5 per gallon in 2030 against about $2.50 for conventional jet fuel. Multiply the gap by mandated volumes and European aviation’s annual compliance bill runs into billions of euros by 2030 — still modest per ticket (single-digit euros on short-haul, tens of euros long-haul at 2030s blend levels), but no longer invisible, much like the carbon-market costs we analyse in carbon credit prices explained.

How compliance actually works: certificates and claims

Neither regime requires every aircraft to burn a physical blend on every flight. Jet fuel is a fungible commodity moving through shared pipelines and airport hydrant systems, so both mandates operate on a mass-balance accounting basis: what matters is that the mandated quantity of certified SAF entered the fuel system, not which wing tank it ended up in.

In the UK this takes the form of tradeable certificates. A supplier that blends more SAF than its obligation earns certificates it can sell to a supplier that blended less, which lets the market find the cheapest route to the aggregate target. The EU relies on supplier-level reporting verified against the Union database for renewable fuels, with each member state’s authority checking annual submissions.

Sustainability certification sits underneath both systems. A litre of used-cooking-oil HEFA only counts if certified under a recognised scheme (such as ISCC) proving its feedstock origin and a lifecycle emissions saving — at least 10% under ICAO rules for CORSIA-eligible fuels, and substantially stricter thresholds under the EU’s Renewable Energy Directive. The paperwork is the point: without traceability, a mandate would simply reward relabelled fossil fuel or fraudulent feedstocks, and used cooking oil imports have already attracted exactly that scrutiny in the road-fuel market.

One further nuance: double counting is prohibited across schemes. A tonne of SAF claimed against the ReFuelEU mandate can also reduce a supplier’s obligation under EU ETS free-allowance rules, but the same environmental attribute cannot be sold separately to a corporate buyer as a voluntary "book-and-claim" credit. As corporate SAF procurement grows, keeping mandate compliance and voluntary claims in separate ledgers is becoming one of the market’s thorniest accounting problems.

How SAF mandates stack with EU ETS and CORSIA

A single long-haul departure from Amsterdam in 2026 can sit under three climate instruments at once. They target different actors and different slices of the same emissions:

The layers are designed to mesh rather than duplicate. Fuel burned as certified SAF carries a zero or reduced emissions factor in EU ETS accounting, so every mandated tonne of SAF also shrinks an airline’s allowance bill; under CORSIA, eligible fuels reduce the offsetting requirement in proportion to their lifecycle savings. In practice the SAF mandate does the physical decarbonisation, while the carbon markets mop up what fuel switching cannot yet reach — and the EU has said it will review whether CORSIA’s weaker price signal justifies keeping long-haul flights outside the ETS after 2026.

Who else is following: mandates beyond Europe

Europe moved first, but the model is spreading. Turkey has announced SAF blending requirements for suppliers; Singapore introduces a 1% SAF levy-funded target from 2026; Japan targets 10% SAF by 2030 via its own supplier obligation; India has signalled indicative blending targets of 1% in 2027 and 2% in 2028 for international flights; and Brazil’s ProBioQAV law phases in emission-reduction obligations from 2027. The United States, by contrast, relies on tax credits and grants rather than a federal mandate — a subsidy-led approach whose future scale is politically uncertain.

For airlines this patchwork is becoming a routing consideration: where fuel must contain mandated SAF, it costs more, and where it does not, tankering rules stop the obvious arbitrage. Which countries’ aviation sectors emit most — and therefore where mandates bite hardest — is mapped in our breakdown of aviation emissions by country.

What the mandates mean for fuel producers and investors

For producers, a SAF mandate is the closest thing energy markets offer to guaranteed demand: a legally binding, decades-long purchase obligation backed by penalties. That is why final investment decisions on European HEFA capacity accelerated sharply after ReFuelEU was agreed, and why the e-SAF sub-target — despite its tiny 2030 percentage — is treated as the anchor customer for the first generation of power-to-liquid plants.

The risks run the other way too: mandate reviews, feedstock caps and slow national enforcement can all strand capital, and the fate of several delayed e-fuel projects shows that a sub-target on paper does not finance a plant by itself. Investors watching the space track three signals above all: national penalty regimes actually entering force, the UK revenue certainty contracts being awarded, and airlines signing long-term offtake agreements beyond their minimum obligations.

What SAF mandates mean for passengers

In 2026, almost nothing visible: at a 2–3.6% blend, the SAF premium adds at most a euro or two to a typical European ticket. By the mid-2030s, at 20% EU blend levels with a growing e-SAF share, credible estimates put the impact at a few tens of euros on long-haul fares — comparable to today’s fuel surcharges and still far below the swings caused by oil prices themselves.

The more meaningful passenger question is what the money buys. Unlike offsets, mandated SAF physically displaces fossil kerosene in the aircraft’s tanks; its emission cuts happen in the sky, not on paper. That distinction — reduction versus compensation — is exactly why regulators paired blending mandates with, rather than replaced them by, offsetting schemes. Understanding both layers is the key to reading any airline’s net-zero claim; our overview of the carbon footprint of air travel puts the numbers side by side.

Related guides: Sustainable Aviation Fuel (SAF) Mandates: What You Need to Know, E-Scooter Safety Rules and The Role of Sustainable Aviation Fuels (SAF) in the Electric vs Hydrogen Era.

SAF decarbonises the routes batteries cannot reach; for the routes they can, our electric aircraft guide shows what is already flying.

Frequently Asked Questions

Sources

• European Commission. ReFuelEU Aviation — Regulation (EU) 2023/2405. transport.ec.europa.eu
• UK Department for Transport. The Sustainable Aviation Fuel Mandate. gov.uk
• Climate Catalyst (2026). Alternative aviation fuel policy in the European Union. climatecatalyst.org
• Carbon Direct (2026). How SAF mandates in the EU and UK are reshaping aviation fuel markets. carbon-direct.com
• Watson Farley & Williams (2025). Fuelling the future: a comparative review of the UK and EU SAF regulations. wfw.com
• IATA. Sustainable aviation fuel production and outlook. iata.org

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