Article 6 of the Paris Agreement: What Every B2B Carbon Buyer Needs to Know in 2026
Article 6 of the Paris Agreement is the international rulebook for trading emissions reductions between countries — and, by extension, the integrity rail that the voluntary carbon market has been waiting fifteen years to plug into. For a CFO or sustainability lead writing a 2026 procurement spec, it is no longer optional reading.
The framework moved from theory to operation in two stages. The 2021 Glasgow rulebook (COP26) closed the double-counting loophole that had haunted the Kyoto-era Clean Development Mechanism. The 2024 Baku decisions (COP29) concluded the operational manual for the Article 6.4 mechanism — methodology approval, registry interoperability, and the standards for the Paris Agreement Crediting Mechanism (PACM). The integrity scaffolding is finally in place.
This briefing is written for the buyer who has to defend a credit purchase to an audit committee. It covers what Article 6 actually says, how 6.2 and 6.4 differ for procurement, what corresponding adjustments mean in practice, how Article 6 interacts with the EU Corporate Sustainability Reporting Directive (CSRD), and a practical checklist for evaluating credits in 2026.
What Article 6 actually says (the plain-English version)
Article 6 of the Paris Agreement sets out how countries can cooperate to achieve their Nationally Determined Contributions (NDCs) — the climate targets each Party submits under the Agreement. It does not create one global carbon market; it creates the legal architecture under which mitigation outcomes can move across borders without being counted twice.
There are three operational sub-articles that matter:
Article 6.2 — bilateral and plurilateral cooperative approaches between countries. Reductions transferred this way are called Internationally Transferred Mitigation Outcomes, or ITMOs. Countries negotiate the terms directly.
Article 6.4 — a centralised, UN-administered mechanism that issues credits against methodologies approved by a Supervisory Body. This replaces the Kyoto-era Clean Development Mechanism (CDM) and operates under the Paris Agreement Crediting Mechanism (PACM).
Article 6.8 — non-market approaches, covering cooperation on capacity-building, finance, and policy that does not involve credit transfer.
For corporate buyers, 6.2 and 6.4 are where the action is. 6.8 is governmental and largely outside the procurement conversation.
The Glasgow rulebook agreed at COP26 was the moment Article 6 became operable. Three fixes mattered:
Corresponding adjustments. When Country A sells a mitigation outcome to Country B, Country A must add an equivalent emission back to its own NDC accounting. The same tonne cannot be claimed twice. This is the structural answer to the integrity criticism that dogged the CDM.
Share of proceeds. A levy — 5% of issued 6.4 units, alongside 2% mandatory cancellation for overall mitigation in global emissions — is directed to the Adaptation Fund to support climate-vulnerable countries.
Kyoto carry-over limits. Pre-2020 Kyoto credits were largely walled off. Only a narrow window of pre-2020 CDM credits could transition, and on tight conditions. This prevented a flood of legacy units undermining the new market.
These three decisions converted Article 6 from aspiration into the integrity infrastructure that buyers can reference in procurement contracts.
What the 2024 Baku decisions actually concluded
After a Bonn intersessional stalemate, COP29 in Baku reached agreement on the remaining operational items for the Article 6.4 mechanism. The Baku outcomes covered:
Standards for methodology approval under the PACM Supervisory Body, including baseline-setting and additionality requirements.
Standards for activities involving removals (as distinct from emission reductions), including monitoring, reporting and reversal-risk management.
Registry interoperability — how the international registry connects to host-country registries and accounts for authorisations and corresponding adjustments.
Authorisation procedures — the formal process by which a host country authorises a 6.4 unit for use towards another country's NDC or for "other international mitigation purposes" (which is the language that captures corporate use).
The practical effect: the PACM is no longer a theoretical mechanism. Methodology submissions and project registrations are proceeding through the Supervisory Body, and the first 6.4-issued units are expected to flow into the market during 2026. See the UNFCCC Article 6.4 mechanism page for the current workstream.
6.2 vs 6.4 — the two pathways that matter to buyers
For a procurement function, the distinction between 6.2 and 6.4 is not academic.
For most corporate buyers in 2026, a 6.4-authorised unit is the cleanest defensible purchase. It is methodology-standardised, registry-traceable, and the corresponding adjustment is logged by the host country at the point of authorisation.
Corresponding adjustments — the double-counting fix in plain English
The single most important integrity concept in Article 6 is the corresponding adjustment.
Imagine Country A reduces a tonne of CO₂ through a forest-restoration project. Without an adjustment, both Country A (because the reduction happened on its territory) and Country B (because it bought the credit) could claim that tonne against their NDCs. The same tonne, counted twice.
The corresponding adjustment forces Country A to add an equivalent tonne back to its national emissions inventory at the moment it authorises the transfer. The net effect: one tonne reduced, one tonne claimed — by Country B. Country A's NDC ledger is unchanged.
For corporate buyers, this matters because "authorised" 6.4 units carry corresponding adjustments. "Mitigation contribution" units — also issued under 6.4 but not authorised for cross-border use — do not. The two unit types are distinct procurement instruments, and the audit committee will want to know which one was bought and why.
What Article 6 means for the voluntary carbon market
Most credits trading in the voluntary carbon market (VCM) in 2026 are not yet 6.4-authorised. They are issued by independent standards bodies and held in independent registries. That does not make them invalid — many are independently verified and publicly tracked — but it does mean their integrity story is different from a 6.4-authorised unit.
The 2025-26 trajectory is convergence. High-integrity VCM credits are increasingly being designed to align with PACM methodologies and to offer optional 6.4 authorisation downstream — meaning the host country can later authorise the credit for cross-border use and apply the corresponding adjustment.
For a procurement spec in 2026, the practical hierarchy is:
6.4-authorised units with corresponding adjustments (highest cross-border integrity).
Independently verified VCM units aligned with PACM methodologies and earmarked for future authorisation.
Independently verified VCM units without 6.4 alignment.
The right answer depends on the claim being made. A net-zero claim under SBTi corporate net-zero standard treatment, or a CSRD disclosure on residual emissions financing, should sit as high up that hierarchy as the budget allows.
What this means for CSRD reporting
Companies in scope of the EU Corporate Sustainability Reporting Directive (CSRD) — phased in from financial year 2024 — must disclose climate transition plans, gross Scope 1/2/3 emissions, and the role of carbon credits in their strategy under the European Sustainability Reporting Standards (ESRS), specifically ESRS E1.
ESRS E1 is explicit that carbon credits cannot substitute for the gross emission reduction trajectory. They are a complement, not a replacement. Where credits are used, the disclosure must specify:
Volume retired and vintage.
Project type and geography.
Standard and registry under which the credit was issued and retired.
Whether the credit is an avoidance or a removal.
Whether the credit carries a corresponding adjustment under Article 6.
The audit-defensible package for residual-emissions financing is therefore the combination of independently verified provenance, a clear avoidance/removal classification, public registry retirement, and — for the strongest claim — Article 6.4 authorisation with a corresponding adjustment. See the European Commission CSRD page for the disclosure framework.
How IMPT positions in the Article 6 era
IMPT's B2B and hotel-booking carbon programmes are designed around three principles that align with the Article 6 integrity logic:
UN-verified provenance. Credits sourced from independently verified, publicly-tracked registries.
On-chain retirement, traceable. Every retirement is logged on a public ledger — the audit-trail equivalent of a registry serial-number receipt, queryable by anyone.
One tonne CO₂ removed per booking. The unit economics are stated and verifiable, not buried in a sustainability annex.
The IMPT corporate programme is built for the Scope 3 reality of business travel: Built-in ESG reporting, automatic carbon offsetting, Scope 1/2/3 ready, EU Compliance, with 5% of travel spend funding climate projects and $0 setup across Starter, Business and Enterprise plans. The retirement evidence flows directly into the CSRD disclosure pack.
Where it is not yet available, the credits used are aligned with Article 6 integrity standards and publicly tracked.
Practical buyer checklist for 2026
The five questions every procurement function should put to a credit seller in 2026:
Is this credit 6.4-authorised or 6.4-aligned? Authorised means it carries a corresponding adjustment from the host country. Aligned means it follows a PACM-compatible methodology but has not been formally authorised.
Is the host country issuing a corresponding adjustment? Without one, the credit cannot be used for a cross-border NDC claim — and increasingly cannot anchor the strongest corporate claims either.
Is the methodology on the PACM list, or referenced to a published PACM-aligned standard? Check the published PACM methodologies index.
Is the retirement traceable on a public registry? The retirement serial number should be queryable by any third party, not just the buyer.
Has the registry's standard been independently reviewed? Independent oversight is the layer that protects the buyer if the issuing standard is later challenged.
These five answers, captured in the procurement file, are the minimum audit defence for 2026.
Common myths — corrected
"Article 6 is just paperwork." It is the integrity rail. Without it, every cross-border claim is exposed to a double-counting challenge.
"All credits are now Article 6 credits." They are not. Most VCM credits trading in 2026 are independently verified but not 6.4-authorised. The two categories coexist and serve different claims.
"Corresponding adjustments make credits too expensive." Authorised units do carry a price premium because the host country is giving up an NDC asset. That premium is the cost of integrity — and for buyers making net-zero claims, the cheaper unauthorised alternative may not be a substitute at all.
"The voluntary market will be banned." The opposite. Article 6 strengthens the framework that supports the voluntary market by giving it a shared integrity standard to converge on. Independent registries are aligning, not disappearing.
"Removals and reductions are the same under Article 6." They are accounted for separately under PACM, with different methodology requirements and different reversal-risk treatments. Buyers should specify which they are procuring.
Frequently asked
What is Article 6 of the Paris Agreement?
Article 6 is the section of the 2015 Paris Agreement that sets out how countries can cooperate to achieve their Nationally Determined Contributions, including through the international transfer of mitigation outcomes. It has three operational sub-articles: 6.2 covers bilateral cooperative approaches and Internationally Transferred Mitigation Outcomes (ITMOs); 6.4 establishes a centralised UN-administered mechanism — the Paris Agreement Crediting Mechanism, or PACM — that issues standardised credits against approved methodologies; and 6.8 covers non-market approaches such as capacity-building. The Article 6 rulebook was finalised at COP26 in Glasgow in 2021 and its operational manual was concluded at COP29 in Baku in 2024.
What's the difference between Article 6.2 and Article 6.4?
Article 6.2 is bilateral: two countries agree directly on the transfer of mitigation outcomes, called ITMOs, with the terms of the deal negotiated between them. Article 6.4 is centralised: it operates under a UN Supervisory Body, issues a standardised unit known as an A6.4ER, and uses a published list of approved methodologies under the Paris Agreement Crediting Mechanism. For corporate buyers, 6.4 is generally easier to access and easier to defend because the methodology, registry and authorisation process are all standardised under UN oversight rather than negotiated case-by-case.
What is an ITMO?
ITMO stands for Internationally Transferred Mitigation Outcome. It is the unit of trade under Article 6.2 — a mitigation outcome that one country authorises another country to use towards its Nationally Determined Contribution, or for "other international mitigation purposes" which captures corporate use. ITMOs are denominated in tonnes of CO₂-equivalent and must be matched by a corresponding adjustment in the host country's national emissions accounting to prevent the same tonne being claimed twice. The specific form and serial structure of an ITMO is set out in the bilateral agreement between the participating countries.
What is a corresponding adjustment?
A corresponding adjustment is the accounting mechanism that prevents double-counting under Article 6. When a host country authorises a mitigation outcome for transfer to another country or for corporate use, it must add an equivalent amount of emissions back to its own NDC ledger. The selling country gives up the climate benefit on its national accounts; the buyer claims it. The result is that one tonne reduced is counted exactly once. Corresponding adjustments are mandatory for authorised units under both Article 6.2 and Article 6.4 and are the structural improvement on the Kyoto-era CDM.
When were the Article 6 rules finalised?
The core rulebook was finalised at COP26 in Glasgow in November 2021, six years after the Paris Agreement was adopted. Glasgow agreed the principles for corresponding adjustments, share-of-proceeds to the Adaptation Fund, and the limits on Kyoto-era carry-over. The operational details for the Article 6.4 mechanism — methodology standards, removals standards, registry interoperability and authorisation procedures — were largely concluded at COP29 in Baku in November 2024 after a Bonn intersessional stalemate. The framework is therefore fully operational entering 2026, with first PACM unit issuances expected during the year.
Are voluntary carbon market credits Article 6-compliant?
Most voluntary carbon market credits trading in 2026 are not formally Article 6.4-authorised. They are issued by independent standards bodies and held in independent registries. They can still be high-integrity, independently verified and publicly tracked, but they are a distinct procurement category from authorised 6.4 units that carry corresponding adjustments. The market is converging: high-integrity VCM credits are increasingly designed to align with PACM methodologies and to offer optional 6.4 authorisation downstream, so a credit purchased today may be authorised later if the host country chooses to apply a corresponding adjustment.
Should companies only buy 6.4-authorised credits?
Not necessarily — it depends on the claim being made. For a cross-border NDC-aligned net-zero claim, 6.4-authorised units with corresponding adjustments give the strongest audit defence. For broader climate-finance contributions, independently verified VCM credits aligned with PACM methodologies can be appropriate, provided the disclosure makes clear that no corresponding adjustment has been applied. The procurement decision should match the claim. A blended strategy — authorised units for the headline net-zero claim, aligned VCM units for additional contribution — is common in 2026 corporate practice.
How does CSRD interact with Article 6?
The EU Corporate Sustainability Reporting Directive requires disclosure under ESRS E1, which covers climate. ESRS E1 is explicit that carbon credits cannot substitute for the gross emission reduction trajectory and must be disclosed separately, including volume, vintage, project type, geography, registry, avoidance-versus-removal classification, and whether a corresponding adjustment has been applied under Article 6. The directive therefore makes the Article 6 status of a credit a disclosable data point. Companies in scope from financial year 2024 should treat 6.4 authorisation status as a procurement-decision input, not a back-office footnote.
What is PACM?
PACM stands for the Paris Agreement Crediting Mechanism, the operational name for the credit-issuing mechanism established under Article 6.4 of the Paris Agreement. It replaces the Kyoto-era Clean Development Mechanism. PACM is governed by a UN Supervisory Body that approves methodologies, registers activities, oversees verification and issues units known as A6.4ERs. Methodologies must meet standards on baselines, additionality, monitoring, leakage and — for removal activities — reversal-risk management. The methodology list and procedural rules are published by the UNFCCC and updated as the Supervisory Body makes decisions.
Will Article 6 raise the price of carbon credits?
For authorised units carrying a corresponding adjustment, yes — there is a structural premium because the host country is giving up an NDC asset when it authorises the transfer. That premium is the price of the integrity claim, and for net-zero-grade procurement it is generally considered defensible. For unauthorised mitigation-contribution units under 6.4, and for independently verified VCM units that are 6.4-aligned but not authorised, prices are lower. The 2026 market is bifurcated: authorised units at a premium, aligned units in a middle tier, and legacy credits at a discount.
