UK Sustainable Aviation Fuel (SAF) Mandate 

The Renewable Transport Fuel Obligations (Sustainable Aviation Fuel) Order 2024 introduces the statutory requirement for fuel suppliers in the UK to deliver a minimum proportion of Sustainable Aviation Fuel (SAF) as part of their total aviation fuel supply, effective from 1st January 2025. For the compliance year 2025, the minimum SAF obligation is set at 2.041%, with mandated volumes scheduled to increase progressively on an annual basis.

The legislation also facilitates the phased introduction of power-to-liquid (PtL) fuels, which are aviation turbine fuels produced from renewable energy sources as a distinct category within the SAF mandate. PtL-specific obligations will be enforced starting from the 2028 Monitoring, Reporting, and Verification (MRV) period.

The obligation for the supply of mandated SAF and PtL will gradually increase each year, aligning with the UK’s strategic objective of achieving net-zero emissions in the aviation sector. This trend is shown in the graph below.

The maximum share of SAF derived from segregated oils and fats (i.e., HEFA) that can be counted toward a supplier’s main obligation will be subject to a declining cap. The table shows the allowed percentage for each obligation period, with the reduction beginning in 2027.

In the context of the mandate, a SAF certificate is a Renewable Transport Fuel (RTF) certificate issued under the Renewable Transport Fuel Obligations (Sustainable Aviation Fuel) Order 2024 as evidence that a specified quantity of sustainable aviation fuel (SAF) meeting defined sustainability and greenhouse gas reduction criteria has been supplied in the UK. Each certificate corresponds to a specific type of SAF, such as HEFA or power to liquid (PtL), and is used to demonstrate compliance with SAF supply mandates under the RTFO scheme. SAF certificates may also be used under the UK ETS to support claims for reduced emissions from aviation activities where recognised.

Scope change

Starting 1st January, 2025, the flights from Northern Ireland to Switzerland will be part of the UK ETS Aviation Activity. Aircraft operators must therefore monitor, report, and surrender allowances for emissions from these flights. The provision requiring aircraft operators to return surplus free allowances (where allocated allowances exceed actual verified emissions) is now extended to cover operators in Northern Ireland.

Developments on the implementation of CORSIA offsetting in the UK

Flights from the UK to the European Economic Area (EEA) and from the UK to Switzerland are currently subject to both the ICAO’s CORSIA (Carbon Offsetting and Reduction Scheme for International Aviation) and the UK ETS (UK Emissions Trading Scheme). Without further policy updates, this overlap will lead to the double-compensating of emissions.

The Environment Agency (EA) is currently evaluating two main policy approaches for managing the interaction between CORSIA and the UK ETS to eliminate duplicate obligations and financial burdens on aircraft operators:

1. UK ETS Only Approach

Under this approach, flights from the UK to the EEA and Switzerland would be covered exclusively by the UK ETS. CORSIA offsetting obligations would not apply under UK legislation for these flights.

• However, this approach would apply only to UK-attributed aeroplane operators.
• Operators attributed to other states would still be subject to CORSIA obligations as per international requirements.

2. Price-Based Hybrid Scheme

Under the price-based hybrid scheme, the aeroplane operator will continue to comply with the UK ETS obligation annually in line with current requirements and be compensated, retrospectively, for the cost of compliance with CORSIA offsetting on flights from the UK to the EEA and Switzerland following the CORSIA compliance deadline every 3 years.

The proposed means of compensating an aeroplane operator include:

• Reduction in UK ETS surrender obligations relative to CORSIA offsetting costs for flights from the UK to EEA and Switzerland.
• Reimbursement with UK ETS allowances proportional to CORSIA offsetting costs for flights from the UK to EEA and Switzerland.
• Direct financial reimbursement for CORSIA offsetting costs for flights from the UK to the EEA and Switzerland.

Conclusion 

In conclusion, the UK’s SAF mandate and related requirements are advancing efforts to reduce aviation emissions. From 2025, fuel suppliers must meet rising SAF blending obligations, with a gradual phase-in of PtL fuels and a cap on HEFA-based SAF. From 2025, UK ETS aviation activity has expanded to cover flights from Northern Ireland to Switzerland, requiring operators to monitor, report, and surrender allowances. With the CORSIA offsetting obligation to fall in place, the Environmental Agency aims to develop pathways where climate neutrality goals are attained, and the events of double compliance and double counting could be avoided.