SAF and RTFO: The Certificate Is Only as Good as What's Behind It

Who’s On the Hook, and When 

Supply 450,000 litres or more of relevant transport fuel in the UK during an obligation year (1 January to 31 December), and RTFO registration becomes mandatory. 

Under the SAF Mandate, which replaced RTFO support for aviation fuels on 1 January 2025, suppliers must register once they own and supply 15.9 terajoules or more of aviation turbine fuel in an obligation year.² 

Each year, obligated suppliers must surrender enough certificates to meet their obligation or pay the buy-out price on any shortfall. Unused certificates can be carried forward for one obligation year, while prior-year certificates can cover up to 25% of the current obligation, providing flexibility without allowing long-term deficit accumulation.¹ 

Verification takes place on Every Claim 

Every certificate is checked before issue—not once a year. 

Verifiers must be recognised by the DfT Administrator, with assurance opinions meeting ISAE 3000 or equivalent standards. ³ 

Voluntary schemes such as ISCC or RSB can support evidence but do not replace recognised verification. 

For SAF, the evidence trail includes invoices, bills of lading and weighbridge records—physical quantity is as important as sustainability. 

Once a methodology for emissions or eligibility is chosen, it must be applied consistently, not changed batch by batch to influence results. ³ 

Not All Feedstocks Are Equal 

Eligibility is defined through DfT feedstock tables that are updated periodically.⁴ 

• Wastes and residues (used cooking oil, agricultural and fishery residues) can earn double certificates per litre or kilogram. 
• RFNBOs such as green hydrogen qualify only when strict energy input conditions are met. 
• Recycled carbon fuels must meet defined RTFO eligibility criteria. 
• Crop-derived fuels are capped under RTFO policy, with the cap on a declining trajectory.⁵  
• Blended or co-processed fuels earn certificates only on the renewable fraction, assessed consignment by consignment. 

Eligibility does not transfer between schemes materials eligible under RTFO may be excluded under the SAF Mandate. 

You cannot trace SAF once it is in the tank 

SAF is typically blended with conventional Jet A-1 because aircraft fuel systems require specific performance characteristics. ² 

Once blended, sustainable and fossil molecules are physically indistinguishable—the sustainability claim survives only through documentation.  

Three elements carry that claim: 

• Blend ratio—supported by testing and production records 
• Proof of Sustainability (PoS)—issued under recognised certification schemes 
• Chain-of-custody records and invoices linking material to claim 

If any one of these weakens, the certificate behind it weakens too. 

Where Double Counting Comes In 

The risk of double-claiming sustainability attributes exists across fuel and carbon markets, which is why traceability and independent verification are central to both schemes. 

RTFO, SAF Mandate, UK ETS, EU ETS and CORSIA operate under different rules, so a claim accepted in one system cannot automatically be assumed valid in another without separate verification. This is exactly what independent verification is designed to catch: the same tonne of feedstock or the same certificate surfacing across two schemes, or a methodology applied one way in one submission and differently in the next. 

The Bottom Line 

Targets make headlines. Certificates only matter if the Proof of Sustainability, chain of custody and blend data behind them hold up and if controls prevent the same environmental attribute being claimed twice. 

That’s the layer that rarely makes the news. That’s the layer Normec Verifavia works in. 

About us 

Normec Verifavia is a leader in third-party verification and has recently been added to the list of officially recognised RTFO and SAF mandate verifiers.

Sources 

¹ RTFO: An Essential Guide – Department for Transport
² UK SAF Mandate: An Essential Guide – Department for Transport
³ SAF Mandate Sustainability Criteria and Verification Requirements – GOV.UK
⁴ RTFO and SAF Mandate List of Feedstocks – GOV.UK
⁵ RTFO Statutory Review and Future of the Scheme – GOV.UK