Four More Programmes In, PACM Conditional: ICAO Widens CORSIA Phase 2 Supply

The UN’s aviation agency has approved four additional carbon crediting programmes to supply eligible emissions units under the second phase of CORSIA, its international aviation offsetting scheme, while conditionally approving the Paris Agreement Crediting Mechanism (PACM) for both current and future periods of the initiative, according to Carbon Pulse. For airlines facing offsetting obligations from 2027, and for the developers and buyers positioning supply ahead of them, the decision enlarges the pool of CORSIA Eligible Emissions Units just as the scheme moves from its first phase into the 2027 to 2029 compliance period.

What ICAO approved

The approvals follow recommendations from ICAO’s Technical Advisory Body (TAB), which assesses emissions unit programmes against the CORSIA Emissions Unit Eligibility Criteria before the ICAO Council decides on eligibility, according to ICAO. TAB recommended the four programmes as immediately eligible to supply CORSIA Eligible Emissions Units for the second phase, covering the 2027 to 2029 compliance period, according to the TAB report excerpt finalized in August 2025.

Source: CarbonMeld — independent carbon credit market intelligence. Document-based quality scores and assessments across all major registries: carbonmeld.com

Alongside the four new approvals, TAB recommended that two programmes remain conditionally eligible for the first phase, the 2024 to 2026 compliance period, according to ICAO. The conditional approval of PACM, reported by Carbon Pulse, marks the first entry of the Paris Agreement’s new UN crediting mechanism into the CORSIA framework, covering both the current period and future ones, subject to conditions that must still be met.

The unit date rules for 2027 to 2029

The TAB report sets out the general eligibility parameters that apply to all CORSIA Eligible Emissions Units approved for the first compliance period of the second phase. Units must be eligible for cancellation toward CORSIA offsetting requirements in the 2027 to 2029 period, issued to activities that started their first crediting period from 1 January 2016, and issued in respect of emission reductions that occurred from 1 January 2021 through 31 December 2029, according to ICAO.

Those dates can only be extended to later timeframes or to unit dates after 31 December 2029 through a Council decision based on TAB recommendations, and only where TAB’s analysis finds a programme fully consistent with all eligibility criteria and guidelines, according to ICAO. The structure mirrors the first phase, where the Council approved parallel parameters at its 228th Session in March 2023, with reductions eligible through 31 December 2026, according to ICAO. The pilot phase parameters, covering 2021 to 2023, were approved at the Council’s 219th Session in March 2020.

Registry obligations and the application pipeline

TAB also recommended that the Council request all programmes eligible for the first phase, as well as programmes the Council decides are eligible for the second phase’s first compliance period, to implement updates to their programme registries where necessary, according to ICAO. Registry functionality is therefore part of the operational compliance burden that comes with approval, not an administrative afterthought.

On the pipeline side, TAB is no longer inviting new applications for first phase eligibility. All previously eligible programmes reassessed in this cycle continue to be eligible for the first phase under their existing parameters. TAB could still make additional first phase recommendations for programmes that respond to its 2026 call for new applications for the second phase, according to ICAO, meaning the 2026 application round can still expand the roster further.

Implications for buyers and developers

For airlines and intermediaries procuring CORSIA eligible units, the immediate effect is a wider approved supply base for the 2027 to 2029 period at a time when demand is set to grow as more routes fall under offsetting obligations. The strict unit date windows mean that not every credit an approved programme issues will qualify: buyers need to verify vintage, activity start date and cancellation eligibility against the general parameters and any programme specific conditions published in ICAO’s CORSIA Eligible Emissions Units document.

For project developers, the signal runs in two directions. Programmes now approved for the second phase offer a confirmed compliance demand channel for post 2020 reductions. The conditional status of PACM, meanwhile, indicates that credits generated under the Paris Agreement’s Article 6 crediting mechanism are on a path toward aviation demand, but the conditions attached to that approval will determine when and on what terms PACM units can actually be cancelled against CORSIA obligations.

What to watch

The first marker is the formalisation of the conditions attached to PACM and to the two programmes that remain conditional for the first phase, and how quickly those conditions are cleared. The second is the outcome of TAB’s 2026 call for new applications, which could add further programmes to the second phase roster. The third is any Council decision to extend unit date eligibility beyond 31 December 2029, which TAB has said it will only recommend where a programme is fully consistent with all eligibility criteria, according to ICAO.