A recurring misconception in voluntary carbon market procurement is that any credit issued under a CORSIA-approved crediting programme is, by that fact alone, CORSIA-eligible. It is not. Programme-level approval by ICAO is a necessary condition, not a sufficient one. Six further layers of eligibility apply at the project, methodology, host-country, and vintage level, each of which can render an otherwise-Gold-Standard credit ineligible for CORSIA compliance in the phase for which a buyer needs it.

This article decomposes the delta between Gold Standard certification and CORSIA eligibility. It is written for developers, procurement teams, and portfolio analysts trying to map a specific pipeline against a specific compliance obligation.

Layer 1: Programme-level approval

The ICAO Council maintains a public list of CORSIA Eligible Emissions Units programmes, updated on recommendation of the Technical Advisory Body (TAB).^[1] Gold Standard for the Global Goals has been an approved programme since the Pilot Phase. Approval is not permanent: the TAB reassesses programmes at defined intervals against ICAO’s Emissions Unit Eligibility Criteria^[2], and approval can be modified, restricted, or withdrawn.

For a buyer, the first-order question is trivially checked: is the programme on the current list for the phase you are buying against? For SaniTap’s projects under Gold Standard for the Global Goals, the answer today is yes — subject to the further layers below.

Layer 2: Methodology and project-type approval within the programme

Within an ICAO-approved programme, only certain methodologies (and hence project types) fall within the CORSIA envelope. ICAO’s approval documents specify which project categories under a programme are in scope. Historically, certain industrial-gas destruction methodologies (HFC-23, N₂O from adipic acid) have been excluded despite the parent programme being approved; some land-use and forestry categories have similarly been restricted or excluded.

Gold Standard’s methodology for Reduced Emissions from Cooking and Heating (“TPDDTEC” v4.0) — the methodology under which SaniTap’s clean cooking credits are developed — and Gold Standard’s methodology for Emission Reductions from Safe Drinking Water Supply (“ERSDWS” v1.0) — for safe water credits — sit within the categories ICAO has recognised as within Gold Standard’s approved envelope, subject to the usual vintage and host-country conditions.^[3]

Layer 3: Vintage windows

CORSIA vintages have progressively tightened. Under the Pilot Phase, credits from vintages 2016–2020 were eligible under specified conditions. Phase 1 (2024–2026) narrowed permitted vintages further. Phase 2 (2027–2035) is expected to tighten further still and — critically — requires corresponding adjustments for all eligible units.

Vintage refers to the year in which the underlying emissions reduction (or removal) occurred, not the year of registry issuance. A project that reduces emissions in 2026 but issues credits in 2027 has vintage-2026 credits. Vintage rules therefore anchor to underlying activity date, and developers running forward pipelines need clarity on when their MRV cycles will produce vintages that hit eligible windows.

For SaniTap’s projects, first credit issuance is expected in late 2026, situating the initial cohort of credits in vintages that sit within the Phase 1 window and are positioned to bridge into Phase 2 as the project pipeline matures.

Layer 4: Host-country authorisation and Article 6

For projects hosted in Non-Annex I countries — a category encompassing most CORSIA project supply — the host country’s formal authorisation is required. The mechanism through which this authorisation flows is Article 6 of the Paris Agreement, whose implementation rules were finalised at the Glasgow CMA (2021) and refined at CMAs 4 through 6.^[4]

The formal object required is a corresponding adjustment by the host country: the host country subtracts the internationally transferred mitigation outcome from its own NDC accounting, ensuring the reduction is not simultaneously claimed by both the host state and the retiring operator. Corresponding adjustments are administratively expensive: they require the host country’s Designated National Authority (DNA), or equivalent Article 6 focal point, to conduct an internal review, sign a Letter of Authorization for specific project vintages, and record the adjustment on an internationally accessible tracking mechanism.

Not every host country has the institutional infrastructure to process authorisation requests at speed. Building the working relationship with the DNA, aligning project documentation to national NDC accounting, and progressing through internal review is itself a multi-quarter workstream. Serious developers should be able to describe where in that process they sit; less serious developers describe an intention.

SaniTap holds a Letter of Approbation from the Government of Madagascar formalising host-country support for the project pipeline. Work continues toward the full Article 6 authorisation for international transfer required for Phase 2.

Layer 5: MRV and no-double-counting integrity

CORSIA expects programme-level and project-level monitoring, reporting, and verification (MRV) that satisfies ICAO’s registry transparency and no-double-counting requirements. In practice, this means:

• Registry systems that publicly disclose issuance, transfer, and retirement transactions, with reasonable audit-trail granularity;
• Procedures for handling voluntary cancellation, reversal, and replacement;
• Chain-of-custody records that enable an auditor to trace a retired credit back to the specific project activity that generated the underlying reduction;
• Clear rules on the treatment of credits issued but not yet retired, including expiry rules and buffer arrangements.

Gold Standard’s public registry and MRV requirements meet these expectations for CORSIA purposes. Where a specific project’s monitoring frequency, sampling design, or data-quality controls fall short of what a CORSIA auditor expects, that is a project-level rather than programme-level failure — which is why serious developers invest in monitoring beyond the methodology minimum.

SaniTap’s projects include third-party sensor monitoring on a randomised sample of installations. This is not required by TPDDTEC v4.0 or ERSDWS v1.0; it is an integrity choice. It generates independent, externally validated corroboration of usage claims, materially strengthening the audit-defensibility of the resulting credits.

Layer 6: Integrity stacking and buyer-side expectations

Even after the ICAO envelope is satisfied, sophisticated buyers apply additional filters. The Integrity Council for the Voluntary Carbon Market’s Core Carbon Principles (CCPs) are one such filter^[5]; corporate net-zero frameworks such as the Science-Based Targets initiative’s Corporate Net-Zero Standard^[6] impose further conditions on the use of credits. A CORSIA-eligible credit is not, by default, a CCP-aligned credit or an SBTi-compliant credit.

The rational developer strategy is to stack integrity: satisfy CORSIA at the eligibility bar and simultaneously satisfy the CCPs, apply gender-responsive certifications, and align MRV with the higher of the two frameworks’ expectations. SaniTap’s credits are designed to do this — Gold Standard-verified, gender-responsive-certified, CCP-aligned, on the CORSIA pathway. The upside for a buyer is that a single credit satisfies multiple accountability frameworks simultaneously.

The three workstreams for the CORSIA pathway

For any project developer targeting CORSIA eligibility from a Gold Standard baseline, three workstreams run in parallel:

1. Host-country engagement for Article 6 authorisation. This is administrative and diplomatic. Timeline is measured in quarters.
2. Programme and methodology alignment — ensuring project documentation, monitoring systems, and registry integration meet CORSIA-approved requirements. Timeline is measured in months per stage; work is largely under developer control.
3. Integrity stacking — securing gender-responsive certification, CCP alignment, and any additional buyer-side integrity frameworks that matter for the target buyer segment. Timeline is measured in months.

The wallclock to full CORSIA eligibility for a Phase 2 buyer is bounded below by the Article 6 authorisation timeline in the specific host country — often 6 to 18 months from initial engagement to Letter of Authorization on a defined vintage cohort. A developer able to describe where in that 6–18 months window they sit, and what specifically is still to be delivered, is a materially different counterparty from one who cannot.

Why the pathway matters for buyers now

The commercial urgency for buyers is not that CORSIA Phase 2 is here yet — it is that the Phase 2 buyer market is being priced today. Airlines and other obligated buyers signing multi-year offtake contracts in 2026 are already forward-purchasing Phase 2-eligible credits at premiums over generic voluntary market credits, and the price differential is expected to widen as the eligibility supply constraint bites.^[7]

For a developer, the strategic response is to be a demonstrable “Phase 2 candidate” — actively progressing on all three workstreams, with credible evidence of progress at each stage. For a buyer, the strategic response is to build forward positions with developers who are demonstrably on the pathway rather than aspirationally on it.

SaniTap’s position summarised

SaniTap’s clean cooking and safe water projects, under Gold Standard for the Global Goals, are positioned as CORSIA Phase 2 candidates. First credit issuance is targeted late 2026; the Letter of Approbation is in hand; work toward Article 6 authorisation is active; and integrity stacking (gender-responsive certification, CCP alignment, third-party sensor monitoring) is above minimum requirements. For a Phase 2 buyer building forward positions, this is the shape of a serious counterparty on the eligibility pathway.

Buyers or partners evaluating specific volumes, vintages, or timing should talk to our commercial team or read the broader SaniTap CORSIA position.