As of January 2025, Calyx Global has updated its GHG Rating scale to AAA-D. This article may reference the old rating scale. Read more here.

The CORSIA tag on the Calyx Global Platform has been updated to better reflect the three phases of compliance periods. 

What is CORSIA

CORSIA (Carbon Offsetting and Reduction Scheme for International Aviation) is the International Civil Aviation Organization’s (ICAO) global market-based measure for international aviation emissions. It requires airline operators to offset the growth in international aviation emissions above a baseline and allows the use of approved carbon credits to offset those emissions. 

CORSIA consists of three phases, each with a 3-year compliance period. The first two phases are voluntary, and the third will be mandatory in 2027 (with some exceptions).

• Pilot phase (2021 to 2023)
• First phase (2024 to 2026)
• Second phase (2027 to 2029, 2030 to 2032, and 2033 to 2035)

Credits eligible for CORSIA

At this time, only credits from carbon crediting programs ACR and ART are approved to supply credits for the first phase. Additionally, for credits to be eligible for the first phase of CORSIA, the project developer must get approval from the host country and a corresponding adjustment (CA) to ensure that the emission reductions or removals are not double-counted. Credits that meet all other requirements but have not yet received host country approval or a CA are considered “CORSIA pending.”

CORSIA tags on the Calyx Global Platform

Within the Calyx Global Platform, projects are tagged as CORSIA-eligible and specify whether they are “CORSIA Pilot Phase” eligible, “CORSIA First Phase Pending” and/or “CORSIA First Phase Approved” (meaning the project has received host country approval and a CA). While we have rated several “CORSIA First Phase Pending” projects, only one is currently approved for the first phase.

For some projects, these tags will only apply on certain vintages depending on exclusions, such as the reporting of sustainable development goal (SDG) contributions, or the issuance of CAs by the host country. In these cases, we will specify this information in the pop-up box under “Learn more.”

While CORSIA eligibility means credits have met certain criteria, it should not be considered synonymous with quality. The following chart shows our GHG ratings for CORSIA-eligible projects compared to projects that are not CORSIA-eligible.

We find that the quality distribution of CORSIA-eligible projects is quite similar to that of CORSIA-ineligible projects; however, there is certainly a lower proportion of highly rated (A and B) credits in the “eligible” category. Airlines purchasing CORSIA credits should perform due diligence and evaluate on a project-by-project basis.

To see the CORSIA tags in action, reach out for a demo.