The UK Department for Transport has opened a Call for Evidence on the SAF Mandate, asking industry to evidence whether the regime’s HEFA cap (from 2027) and PtL obligation (from 2028) will hold once binding supply pressures arrive. The CFE runs from 16 June to 11:59am on 28 July 2026 and asks nine specific questions.
The opening is significant for what it does not propose. DfT is not consulting on changes; it is asking for evidence that maintaining the current design would cause significant harm to industry and consumers. The default is status quo. Industry has 42 days to evidence that the HEFA cap and PtL obligation, if maintained as written, would cause that significant harm.
The numbers explain why DfT is asking. The non-HEFA obligation rises to 7.7% of the mandated SAF volume in 2027. The HEFA cap limits HEFA-pathway certificates to 71% of a supplier’s SAF obligation in 2030, sliding to 35% in 2040. The PtL obligation starts at 0.2% in 2028 and climbs to 3.5% by 2040. SkyNRG and ICF’s 2026 outlook, published the day before the CFE opened, put operational global eSAF capacity in 2030 at just 0.2 million tonnes against EU eSAF demand of around 0.6 million tonnes under ReFuelEU’s 1.2% sub-mandate. On those numbers the gap is roughly 3x for EU obligations alone, before the UK PtL trajectory is layered on top.
“Buyout does not deliver the carbon savings that the SAF Mandate is designed to deliver.”
That pull quote is DfT’s own framing in the CFE document. It is the cleanest signal that the department views buyout as a poor compliance outcome rather than a price ceiling, and it explains why the CFE’s longest single section is on flexibilities. Prior-year certificate redemption is currently capped at 25% of the obligation; the CFE explicitly asks whether to raise that ceiling. Multi-year certificate carryover, ZEV-style obligation banking and borrowing, and RTFO-style bonus certificates for advanced fuels are all enumerated as options. None of these change the obligation itself; they change the temporal and pathway flexibility around it. Direct adjustments to the HEFA cap and PtL obligation, raised in Q3 and Q5, sit alongside as the more interventionist set.
Tankering is a second major theme, covered by Q8. DfT acknowledges that the SAF Mandate may worsen tankering, the long-standing practice of airlines uplifting extra fuel at lower-cost airports to reduce uplift at higher-cost ones, by widening the per-litre cost gap between UK and non-UK fuel. No anti-tankering measures are proposed; industry has the burden to demonstrate scale of any incremental effect.
Watch the £219 million Low Carbon Fuels Fund DfT announced the same day the CFE opened. The fund is meant to underwrite UK SAF production capacity, and its allocation pace through Q4 2026 will be the cleanest read on whether DfT believes domestic ATJ and PtL FIDs can plausibly close the non-HEFA gap before the HEFA cap and PtL obligation bind. Allocations announced before the CFE response is published will shift the centre of gravity in the consultation toward flexibilities; a slow fund deployment will strengthen the case for direct cap or obligation adjustments.
Source: UK Department for Transport
