A CORSIA Eligible Emissions Unit is a carbon credit that can be cancelled by an airline for CORSIA compliance. The credit has to come from an emissions-unit programme that ICAO has approved for the relevant compliance period, and it also has to satisfy the scope limitations attached to that approval.
This is where many project developers get caught out. A registry can be credible, a methodology can be respected, and a project can still fail CORSIA eligibility if the crediting period, vintage, host-country treatment or activity type falls outside the approved scope.
Who decides eligibility?
ICAO's Technical Advisory Body reviews emissions-unit programmes against the CORSIA Emissions Unit Eligibility Criteria. ICAO then publishes eligible programme decisions and summary tables. These tables are the practical starting point for any project developer or buyer trying to understand whether a credit can be used for CORSIA.
Programme approval is not a blank cheque. The approval can be limited by vintage, activity type, country, methodology, unit type, crediting-period start date or additional conditions.
What has to be checked
- Programme: the registry or programme must be approved by ICAO for the relevant CORSIA phase.
- Unit type: the credit type must sit inside the approved programme scope.
- Vintage: the emission reduction or removal year must fit the CORSIA vintage window.
- Crediting-period start: CORSIA rules restrict older crediting periods for many routes.
- Host-country authorisation: relevant units need protection against double claiming through authorisation and corresponding-adjustment treatment.
- Methodology restrictions: some programme approvals exclude or limit specific methodology categories.
Host-country authorisation is now central
For many post-2020 units, the practical question is not just whether the programme is on the ICAO list. It is whether the host country has authorised the mitigation outcome for use toward CORSIA and applied, or committed to apply, the accounting treatment needed to avoid double claiming under Article 6-style accounting.
In plain terms: a credit cannot credibly be used by both the host country toward its climate target and an airline toward CORSIA. Host-country letters of authorisation and corresponding-adjustment processes are therefore a major supply bottleneck.
Examples of programme routes
As of the April 2026 ICAO eligibility material, major approved or conditionally approved routes include programmes such as the American Carbon Registry, Architecture for REDD+ Transactions, Climate Action Reserve, Gold Standard, Global Carbon Council, Isometric, Verra VCS and jurisdictional/nested REDD+ routes, alongside several conditional approvals. The exact scope changes over time, so the current ICAO summary table should be treated as the source of truth.
That range matters. CORSIA is not only a nature-based market, and it is not only an avoidance market. But each route has its own restrictions. For example, a removal programme may be approved for particular carbon removal categories, while a broad registry may have excluded methodologies or vintage limits.
Developer diligence checklist
- Start with the current ICAO eligible-units page, not a buyer rumour or old broker deck.
- Check the exact programme row, footnotes and scope limitations in the ICAO summary table.
- Ask the registry what CORSIA labelling, authorisation and cancellation evidence will look like.
- Confirm whether the host country is willing and able to issue a letter of authorisation.
- Keep buyer language conservative until the units can be clearly shown as CORSIA eligible.
If you are comparing registry routes, start with standard fit before modelling CORSIA revenue upside.
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