A carbon credit’s integrity is a stack, not a checkbox. Most credits on the voluntary market clear one bar: registered under one methodology on one registry, verified once, retired once. That is the industry baseline and it is not enough for the buyers whose money now moves the market: CORSIA-obligated airlines, corporate ESG procurement teams facing SEC and CSRD scrutiny, and sovereign compliance buyers under Article 6.

SaniTap develops credits to a higher standard: an integrity stack of six independent bars, each defending the credit against a different type of challenge. This article sets out what integrity stacking is, why the stack matters more than any single layer, and the specific stack SaniTap operates today.

The six layers of the SaniTap stack

The stack, from foundation upward:

1. Gold Standard for Global Goals registration. The credit is developed under Gold Standard’s TPDDTEC v4.0 methodology (improved cooking) or ERSDWS v1.0 (safe water) and cleared through Gold Standard’s design review, validation, monitoring and verification cycle. This is the base bar: an internationally recognised programme with continuous scrutiny. Every credit issued carries a Gold Standard serial number and a full public paper trail on the registry.

2. Gender-responsive certification. Gold Standard’s higher-tier optional certification. Where the mandatory baseline requires do-no-harm on gender, gender-responsive requires proactive gender analysis, targeted actions to advance gender equality, and gender-disaggregated monitoring at every stage. The certification is materially harder to obtain than the base standard and is publicly visible on the credit itself.

3. ICVCM Core Carbon Principles alignment. The Integrity Council for the Voluntary Carbon Market’s Core Carbon Principles are a global framework for assessing carbon-crediting programmes against 10 integrity criteria (additionality, permanence, robust quantification, no double counting, transparency, governance, positive sustainable-development impact, safeguards, and more). ICVCM alignment is a programme-level assessment conducted by an independent third party; it is not something a project awards itself. SaniTap’s credits are developed to align with the CCPs, which is one of the harder-to-forge integrity signals in today’s market.

4. Third-party sensor monitoring on a randomised sample. Gold Standard’s methodology requires periodic monitoring; SaniTap goes further, deploying independent third-party sensor monitoring on a randomly selected sample of installations. This is hardware verification, not self-report, and it is conducted by an entity SaniTap does not control. When a buyer asks “how do you know the stoves are being used” or “how do you know the water pumps are still operational”, the answer includes an independent sensor stream that neither SaniTap nor the local implementing partner can influence.

5. Article 6 Letter of Approbation from the Government of Madagascar. Under the Paris Agreement Article 6, credits used for internationally-transferred mitigation outcomes require host-country authorisation. SaniTap holds a Letter of Approbation from the Government of Madagascar, formally endorsing the programme as eligible for international transfer. This is the government-level authorisation without which CORSIA phase-2/3 credits cannot be used. It represents sovereign endorsement, and it is prerequisite for CORSIA eligibility.

6. Actively progressing toward CORSIA eligibility. SaniTap is on the pathway to CORSIA Phase 2/3 eligibility under ICAO’s Technical Advisory Body assessment. This means the programme is being developed against the specific criteria CORSIA-obligated airlines will need to see: corresponding adjustments, host-country authorisation, methodology approval, and vintage windows. Airlines making forward-buying decisions in 2026 need credits with a documented CORSIA pathway, not credits retrofitted after the fact.

Why the stack matters more than any single bar

An adversarial buyer, journalist, or auditor challenging a carbon credit typically challenges one dimension: additionality, permanence, host-country claims, gender safeguarding, methodology conservatism, monitoring rigor. A single-standard credit stands or falls on how well it can defend that one dimension.

A stacked credit answers the challenger by pointing past the challenge. If the additionality of the underlying methodology is questioned, the ICVCM CCP assessment stands independently. If the monitoring is questioned, the third-party sensor stream stands independently. If the gender claims are questioned, the higher-tier certification stands independently. If the host-country claim is questioned, the Article 6 Letter of Approbation stands independently.

No single layer is unassailable. The sum is materially harder to unwind than any part.

Why CORSIA-obligated buyers care about this now

CORSIA Phase 1 (2024-2026) has run on a small pool of eligible credits. Phase 2 (2027-2035) tightens the criteria and increases the volume airlines must retire. Airlines are placing forward orders now against credits they expect to be eligible at retirement time.

The credit that survives that gap between purchase and retirement is the credit that carries the most independent integrity signals. A credit that meets only the ICAO minimum in 2026 can lose eligibility if the criteria tighten. A credit that meets the ICAO minimum plus five additional independent standards is far more resilient across a five-to-nine-year holding period.

This is the buyer-side logic behind integrity stacking: not “belt and braces” for its own sake, but forward-defence against the specific criteria evolution CORSIA is likely to go through between now and 2035.

For corporate ESG buyers

The same logic applies to corporate ESG and net-zero buyers. Frameworks tighten. The Science Based Targets initiative, the ISSB, CSRD, SEC climate rules all continue to raise the credibility bar credits must clear. A credit purchased in 2026 to defend a claim in 2030 has to carry evidence that satisfies whichever framework version applies in 2030, not just the version current at purchase. A stacked credit carries more forward-optionality than a single-standard credit at the same price point.

What buyers can verify independently

Every layer of the stack is externally verifiable:

  • Gold Standard credentials on the Gold Standard Registry
  • Gender-responsive certification listed as an attribute on the credit
  • ICVCM CCP alignment status on the ICVCM assessment portal
  • Third-party sensor monitoring reports available on due-diligence request
  • Article 6 Letter of Approbation available on due-diligence request (redacted commercial terms)
  • CORSIA eligibility pathway documented in the project’s Preliminary Assessment

None of these depends on trusting SaniTap’s own claims. The stack is designed to be independently defensible layer by layer.

The one-line summary

An integrity-stacked credit is a credit that would defend well in a hostile due-diligence session across six independent dimensions, not just one. That is what SaniTap develops, and that is what CORSIA-obligated airlines and serious corporate buyers should be asking every project developer for.

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