CORSIA-Eligible Units: A Buyer's Checklist for Airlines

Six checks to run before an airline pays for carbon units meant for CORSIA, the evidence to request from a seller for each one, and the warning signs that should pause a deal.

A carbon credit can be perfectly good and still be useless for CORSIA. The scheme only accepts units that pass a specific set of tests, and the airline carries the risk if a unit later turns out not to qualify. This checklist is the one we use when sourcing for operators. Print it, tick each line, and do not sign until every line has evidence behind it.

Before you start: write down the period

Every eligibility test depends on which compliance period the units are meant to cover. Before you speak to any seller, note:

the compliance period (for example, the first phase, 2024–2026)
the volume you expect to cancel
the date by which you need the units in your account

Put these at the top of your requirement. If you post it through our buyer intake form, there are fields for CORSIA conditions, accepted programmes and vintages so sellers see the constraints up front.

The checklist

1. Approved programme

The units must be issued by a crediting programme that ICAO has approved for that compliance period. Approval is given programme by programme and period by period, and it can come with conditions on which project types or dates are included.

Ask the seller for: the programme name and the registry ID of the project, then confirm the programme against ICAO's current list yourself on ICAO's CORSIA pages. Do not rely on a seller's summary of the list.

2. Vintage inside the window

Vintage is the year in which the emission reduction or removal happened. Each compliance period has an eligible vintage window, and units from outside it do not count, however cheap.

Ask for: the vintage of every unit in the lot, ideally shown on the registry record, not just a sales sheet. A lot that mixes vintages should be broken down line by line.

3. Host-country authorisation and corresponding adjustment

For current periods, the country where the project sits must authorise the units for use in international schemes like CORSIA and apply a corresponding adjustment. That adjustment is an accounting entry that takes the tonnes out of the host country's own climate target so the same reduction is not counted twice. Our plain guide to corresponding adjustments explains it further.

Ask for: the host-country letter of authorisation (or its reference), and evidence of how the label or attribute showing the adjustment appears on the registry. If the seller says authorisation is "in progress", treat the lot as forward risk and price and contract it that way.

4. Eligible label on the registry

Many programmes mark units that meet CORSIA conditions with a specific label or attribute in their registry. This is the quickest independent check you have.

Ask for: the serial number range, then look it up on the programme's public registry. The label, vintage and status (issued and not yet retired or cancelled) should all match what you were told.

5. Clean ownership and no prior use

The units must be held by the seller, or by someone they can bind, and must not already be retired, cancelled or pledged elsewhere.

Ask for: a registry statement or screenshot of the holding account, plus a written confirmation that the units are unencumbered. Our article on registries and serial numbers shows how to read a serial range.

6. Project documents

The standard set: Project Design Document, validation report, latest verification report and the issuance record. These do not prove CORSIA eligibility on their own, but they let you see that the project is what it claims to be.

Ask for: all four, and check that the methodology, project boundaries and dates line up with the registry entry. On this desk, these are shared with qualified buyers before any contract.

A quick summary table

Check	Evidence	Who confirms
Programme approved for the period	Programme name, project registry ID	Your team, against ICAO's list
Vintage in window	Registry record per unit	Your team, on the public registry
Authorisation and adjustment	Host-country letter, registry attribute	Seller provides; your team checks
Eligible label	Serial range lookup	Your team, on the public registry
Clean title	Holding statement, written confirmation	Seller; reflected in the contract
Project documents	PDD, validation, verification, issuance	Your team or adviser

Warning signs

Pause the deal if you see any of these:

The seller will not share serial numbers until after payment.
The vintage is described as a range ("2021 to 2024") with no breakdown.
Authorisation is mentioned verbally but nothing is in writing.
The price is far below other eligible offers without a clear reason.
The units sit in an account the seller cannot show you.

After purchase

Once you are satisfied, the units move into your registry account, or are cancelled on your behalf with your airline named. Cancellation is then reported to your national authority (the DGCA in India). Keep the full evidence file with your annual records; your verifier and authority may ask to see it.

If you would like a second pair of eyes, unit sourcing and due diligence are part of our CORSIA services, and we can run this checklist against any offer you already hold.