7 lessons from the first year of ReFuelEU’s 2025 SAF mandate
Ashraf Hoseini
Environmental Strategy Lead
-
SITA
What if I told you that SAF can be compliant, delivered and fully paid for — and still not give you the expected benefit?
Sadly, that is the reality many airlines encountered after completing the first ReFuelEU reporting round with the 2% SAF mandate.
On paper, everything worked as intended. SAF was uplifted, supplier compliance requirements were met, fuel was physically delivered, and invoices were settled. From a technical point of view, emissions should therefore have gone down.
However, when it came time to report — and to claim that value under EU ETS — the system didn’t line up.
To understand what really happened, my team and I at SITA organized a session called Breaking Net Zero Silos.
The first session focused on SAF management and the real challenges airlines, fuel suppliers and verifiers face in practice. We brought these groups together to compare experiences and look at what happens once SAF moves from intent to execution.
ReFuelEU quickly became central to the discussion. Most SAF today sits within that mandate, and many of the challenges surfaced through it.
What came out of those discussions were seven lessons the industry needs to reflect on.
Lesson one: SAF can be compliant, delivered and still unclaimable
The first lesson was also the most confronting.
Several airlines described situations where SAF met fuel supplier compliance requirements under ReFuelEU, was physically delivered and fully paid for, yet could not be claimed under EU ETS.
One specific example discussed was animal fats category 3. This feedstock was accepted for ReFuelEU compliance and used by suppliers, but its eligibility for EU ETS airline claims was not clearly recognised in existing guidance. As a result, airlines had to seek explicit approval from their competent authority, with different outcomes depending on which authority they reported to.
In practice, the same fuel led to different claiming results.
Lesson two: the same activity can lead to different outcomes
Verifiers explained that identical SAF activity didn’t always lead to the same claim outcome.
Whether SAF could be claimed depended largely on how national authorities interpreted the regulations. This meant that airlines in very similar situations experienced different results, while verifiers were unable to apply a single, consistent approach across their portfolios.
This wasn’t about anyone acting in bad faith. It was about a system where the regulations exist, but their interpretation isn’t aligned across borders, making outcomes difficult to predict.
Lesson three: documentation doesn’t always travel across borders
Another issue that surprized many of us was how difficult it can be for documentation to move between national systems.
SAF documentation issued under one national framework wasn’t always immediately recognized elsewhere. One example discussed was France’s Carbure system. Documentation required by French authorities wasn’t initially accepted by Germany for EU ETS claims and only became accepted after further clarification.
By the time this clarification arrived, the fuel had already been delivered, and the reporting window had narrowed, leaving airlines with limited options to recover the value.
Lesson four: allocation decisions can erase value
Fuel suppliers were open about the constraints they operate under, including supply availability, mandate requirements, infrastructure limitations and commercial realities.
Even when suppliers try to allocate SAF in a way that maximizes airline benefit, this isn’t always possible. One scenario discussed involved SAF being delivered at an airport where an airline operated, but on non‑EU‑ETS‑eligible flights, such as long‑haul services.
The SAF was real and so was the emissions reduction. However, the regulatory benefit couldn’t be realized.
Lesson five: one SAF, multiple schemes and multiple data requirements
Verifiers highlighted another layer of complexity: different schemes require different data.
For example, EU ETS accepts standard density and doesn’t always require proof of purchase, while UK ETS requires actual density and proof of purchase. CORSIA, in turn, requires ICC-CORSIA certification, and ICC-EU certification alone isn’t sufficient.
As a result, SAF that cannot be claimed under one scheme cannot automatically be transferred to another. What looks flexible in theory becomes rigid in practice.
Lesson six: timing turns complexity into risk
Timing amplified all of these challenges.
Fuel suppliers explained that final SAF volumes and documentation often become available late in the year, sometimes depending on upstream producers. Verifiers confirmed that documents — and corrections — frequently arrive close to, or even after, the 14 February auditing deadline.
This leaves airlines with very limited time to clarify eligibility questions, request authority approvals or adjust claims before submission.
In several cases, airlines made a deliberate decision not to claim parts of their SAF volumes because the documentation arrived too late to manage it with sufficient confidence.
Lesson seven: manual processes are straining the system
The operational burden involved is massive.
One fuel supplier issued around 3,500 SAF documents in a single reporting cycle. Verifiers reviewed hundreds of documents across airline portfolios, most of them shared as PDFs in different formats and with varying terminology.
This level of manual effort is difficult to manage today and impossible to scale tomorrow.
My takeaway after the session
Regulations are designed to incentivise SAF uptake by allowing airlines to benefit from using it. The experience and feedback from many airlines has shown, however, that turning SAF uplift into realized value is currently harder than intended.
When airlines invest in SAF and later discover that expected claims are uncertain or impossible, frustration follows and motivation erodes. Motivation, however, is essential if SAF is to scale at the pace aviation needs.
The positive takeaway is that we now have something powerful: real evidence from real reporting cycles. These experiences show where value is lost — misalignment between regulations, data, documentation and timing.
Looking ahead, these same challenges will also matter beyond regulatory reporting. Traceability, allocation and trusted data are equally critical for future Scope 3 attribution and passenger‑facing transparency. Without a system that reliably connects SAF use to recognized value, those future use cases will face similar obstacles.
SAF is therefore not just about fuel. It is about trust in the system and data that sits around it.
And trust is what will ultimately determine how fast we can decarbonize aviation.