Two words that sound alike
Both words describe paying for an emissions reduction you did not make with your own hands. The difference is where the reduction happens. In carbon accounting, where is nearly everything: it decides which ledger the reduction can enter, and what an auditor will ask to see behind it.
What an offset is
An offset is a reduction or removal bought outside your own value chain. Funding forest protection, or a renewable energy project on another continent, to counterbalance emissions you have produced: the project is real, but it has no connection to the activities in your own inventory. The instrument that records it is usually a carbon credit, a tradeable unit representing one tonne of CO₂ reduced or removed by that external project.
Offsets have their own market, their own standards and their own debates. This lesson is not that debate. The point here is narrower: an offset compensates for your emissions somewhere else. It does not reduce them.
What insetting is
An inset is a reduction made inside your own value chain, where the emissions happen. If your people fly, the flights sit in your Scope 3, and aviation fuel is inside your value chain. When sustainable aviation fuel (SAF) replaces fossil fuel in that system, the reduction happens in the same chain of activity your inventory already counts.
That is the whole distinction. Not a better class of project: a different location in the accounts.
Where a SAF certificate sits
A SAF certificate records the verified environmental attributes of a batch of SAF: the lifecycle reduction, the feedstock, the pathway and the certification behind it. A registry allocates it to one owner and retires it once, so the claim is counted once. Because the fuel replaces fossil fuel inside aviation, the reduction reports against your Scope 3 travel or freight line, not as a purchase from outside your inventory.
A SAF certificate is an inset, not an offset, and it is not a carbon credit. The distinction is visible in the paperwork. Our May 2026 retirement on the RSB Book and Claim Registry names the batch, 36.213 tonnes of certified SAF at 80.674% below the fossil baseline, and names both claimants: Delta Air Lines on the Scope 1, our own legal entity on the Scope 3. A carbon credit names a project. A retirement statement names the fuel, and the registry lesson shows that machinery in detail.
What a SAF certificate does not do
The limits are part of the instrument, and knowing them is what makes the claim defensible.
It does not make a flight’s emissions disappear, and we will not describe it that way. It discharges no blending mandate, levy, or trading-scheme obligation: our volume sits in the voluntary market, above what regulation already requires. And the Scope 3 claim is capped at your actual footprint in the sector for that year, so a certificate can never say more than your own travel did.
For target setters, the SBTi Corporate Net-Zero Standard version 2 permits commodity certificates on a book-and-claim chain of custody, subject to its integrity criteria. Permits is the exact verb: the standard sets guardrails and leaves certification to the schemes that do it.
The question to take away
When someone shows you an emissions instrument, ask where the reduction happened. Outside your value chain, it compensates. Inside it, it reduces, and it can enter the ledger your targets are measured against. What a SAF certificate is and whose emission is whose are the next two steps.