Article 6 of the Paris Agreement—ITMOs, corresponding adjustments, and the carbon market—is where climate accounting stops being “just” a matter of projects and private registries and becomes a matter between States: who can use a mitigation outcome, for what purpose, and how double counting is avoided. This is where ITMOs and the corresponding adjustment (CA) come in—the accounting adjustment that prevents the same tonne from being claimed twice.

What is an ITMO under Article 6, and how does it differ from voluntary carbon market (VCM) credits?

An ITMO is, in practice, an internationally transferred mitigation outcome transferred between Parties (States) under the cooperative approaches of Article 6.2. The key difference is that an ITMO is not “simply” an offset traded between private actors: it is a mitigation outcome that enters accounting against NDCs (nationally determined contributions) and into UN transparency reporting. Source: OECD (2022).

The typical B2B use cases are three. The key point is that what changes is “rights of use” and accounting—not just the name of the unit. Source: OECD (2022).

  1. Use toward the buyer’s NDC (another Party) The unit serves a buyer country for its own NDC balance. Here, the rules on authorization and corresponding adjustment are central.

  2. OIMP (Other International Mitigation Purposes) The unit is used for international purposes other than NDCs—for example, international schemes or sectoral programs. Here too, when authorized and transferred, accounting rules are triggered.

  3. Mitigation contribution (contribution) Here the point is not to “transfer” an outcome for another country to use. Mitigation is financed in the host country and the outcome remains within its NDC boundary. This is also a different setup for corporate claims.

In the voluntary carbon market (VCM), by contrast, demand is typically corporate or financial and NDC rules do not automatically apply. Under 6.2 and 6.4, on the other hand, there is a sovereign element: authorization by the host State, reporting, and—where applicable—corresponding adjustment to avoid double claiming between countries. Source: OECD (2022).

A practical buyer-side example makes the difference clear. A multinational can buy VCM credits (for example VCUs or Gold Standard credits) and make a voluntary claim. But if it wants an “Article 6-aligned” asset, it will generally look for units that are authorized and tracked as ITMOs or as an authorized A6.4ER with evidence of CA. Source: ICVCM.

This is where the interplay between VCM and compliance comes in. The debate on CA in the voluntary space is open: it is not always required or desired, but some host countries may start requiring authorizations and CA even for “voluntary” projects to protect their own NDC. Source: OECD (2024).

What is a corresponding adjustment: when it is mandatory and how it works in national registries

A corresponding adjustment is an accounting adjustment that avoids double counting and double claiming between States. Operationally, when an ITMO is transferred, the Parties’ NDC accounting is “adjusted” consistently: the buyer and the transferring country record the transaction with opposite signs, under rules that also depend on the type of NDC. Source: OECD (2022).

CA is mandatory when a mitigation outcome is authorized for use toward another Party’s NDC or for OIMP and is first transferred under Article 6.2. For Article 6.4, when an A6.4ER unit is authorized and then transferred, it becomes an ITMO and requires CA. Source: Legal Response International (Explainer, 2025).

It is:

  • Authorization: the sovereign decision (letter/statement) specifying permitted uses and conditions, including the definition of the first transfer trigger for certain purposes.
  • Corresponding adjustment: the accounting and reporting act that follows that trigger. Source: OECD (2022).

On the technical “how,” infrastructure matters. Countries can use national registries or UNFCCC services. For 6.2 there is registry and reporting infrastructure connected to centralized platforms. For 6.4 there is a UNFCCC mechanism registry and links with 6.2 systems. Source: Florence School of Regulation (EUI).

In B2B due diligence, the question is not “is there CA?” in the abstract. The question is: who guarantees it, when does it trigger, and what happens if it does not arrive. In practice, it makes sense to ask for evidence of:

  • host-country authorization;
  • unique identifiers (serial/ID), vintage, volume, authorized purpose;
  • proof of CA or at least “CA pending” with timelines and contractual responsibilities. Source: OECD (2022).

Article 6.2 vs 6.4: what rules change for transfers, authorizations, and environmental integrity

The most concrete difference is governance. Article 6.2 enables bilateral or plurilateral cooperative approaches: UN rules and reporting, but implementation is closely tied to national agreements and systems. Article 6.4 is a centralized UN mechanism (the Paris Agreement Crediting Mechanism) with a Supervisory Body and a dedicated registry. Source: FSR (EUI).

The units also differ. Under 6.4, A6.4ERs are issued; if authorized and transferred internationally, they become ITMOs. Under 6.2, ITMOs can be transferred from domestic programs or activities, provided they meet guidance and reporting requirements. Source: Legal Response International (2025).

On environmental integrity and “system costs,” 6.4 includes two elements that directly affect the net deliverable volume and therefore pricing:

  • Share of proceeds for the Adaptation Fund (a 5% deduction of credits).
  • OMGE (overall mitigation in global emissions) with a minimum 2% cancellation at issuance. Source: Climate Action Transparency (Article 6 guide).

On authorizations and uses, 6.2 requires clarity on what is authorized (NDC vs OIMP) and on what counts as first transfer. 6.4 also allows the mitigation contribution logic (units not authorized for transfer) and may allow subsequent authorizations, with operational implications to be assessed case by case. Source: Legal Response International (2025).

For intermediaries and buyers, the practical effect is this: 6.2 is often more “deal-driven” and can fragment documentation and responsibilities across State-to-State arrangements and commercial contracts. 6.4 tends to standardize MRV and issuance, but in the start-up phase availability may be limited and procurement timelines longer. Source: FSR (EUI).

How to read an “Article 6-ready” credit: documents, labels, and risk signals for buyers and intermediaries

“Article 6-ready” only makes sense if it means something verifiable. For a B2B buyer, it means having a package that demonstrates: host-country authorization for a specific use, first transfer rules, and a credible commitment on corresponding adjustment and disclosure. Source: OECD (2022).

The typical documents to request are few but non-negotiable:

  • letter/statement of authorization;
  • agreement or framework document with the host country (if applicable);
  • evidence of registration and serialization;
  • MRV reports and verification;
  • if 6.4, evidence of deductions and cancellations (share of proceeds and OMGE) and registry rules. Source: Legal Response International (2025).

In the voluntary market, some quality labels can help but do not replace Article 6. ICVCM’s CCPs are an integrity signal in the VCM, but CCP does not automatically mean ITMO or CA, and Article 6 does not directly “regulate” the VCM. Source: ICVCM.

The most common red flags are repetitive—and precisely for that reason, expensive if you ignore them:

  • “Paris-aligned” claims with no proof of authorization;
  • confusion between private registries and national or UNFCCC registries;
  • promises of CA “on request” with no clear legal responsibility;
  • political and regulatory risk in the host country, including pauses or policy changes. Source: World Bank (risk of corresponding adjustment).

A useful procurement example: in a tender for hard-to-abate sectors, you can ask for “units authorized for OIMP with CA at first transfer” and include remedies if CA is not applied or if authorization is revoked. Source: OECD (2022).

What this means for the carbon market: prices, credit availability, and strategies for companies with net-zero targets

Oversupply does not eliminate the premium for “rights of use.” The World Bank notes that the global pool of unretired credits approached around 1 billion tCO₂ in 2024, and that compliance demand has grown much faster than voluntary demand. This helps explain why, even in a market with abundant supply, authorization and accounting can create “quality” scarcity. Source: World Bank, State and Trends of Carbon Pricing.

The so-called Article 6 premium comes from three practical factors: reduced double-claiming risk, eligibility for more robust claims, and potential use in regulated schemes or OIMP. In this sense, Article 6 of the Paris Agreement—ITMOs, corresponding adjustments, and the carbon market is not only about compliance: it is also a procurement and reputation issue. Source: OECD (2024).

Availability, however, is not “plug and play.” 6.2 grows through bilateral agreements and pilot pipelines, but many transactions are still early-stage and require MRV and registry capacity in host countries. This translates into long lead times and more points of contractual failure. Source: FSR (EUI).

For companies with net-zero targets, the strategies that typically hold up best under scrutiny are three:

  1. separate offsetting and contribution in claims, and tie them to the unit type;
  2. build “layered” portfolios with high-integrity VCM credits and a share of authorized Article 6 units, to manage availability and risk;
  3. use forward contracts with conditions on authorization and CA and clear fallbacks. Source: OECD (2024).

Reputational risk today concentrates on accounting and claimability. Due diligence shifts from “price per tonne” to “rights of use, accounting, disclosure, and audit trail,” with verifiable evidence from registries and transactions. Source: OECD (2022).

Note on COP30 2025: Article 6 rules have been negotiated and implemented progressively, and the market remains sensitive to operational clarifications and to host-country choices on authorizations and CA. In practice, for buyers the point is not to predict the political outcome, but to contract properly for what happens if policies change.

Operational checklist to avoid double counting and greenwashing (claims, contracts, and due diligence)

The claim comes before the credit. Define upfront whether you want to make an offset claim or a contribution claim, and link it to the unit type: an ITMO with CA when required, or a VCM credit without CA if you are making a contribution and you disclose it correctly. Avoid ambiguous formulas like “Paris compliant” without evidence. Source: OECD (2024).

Minimum due diligence must cover both the unit and the rights of use:

  1. serials, vintage, volume;
  2. proof of retirement or cancellation;
  3. host authorization and authorized uses;
  4. evidence of the trigger and CA status;
  5. checks on methodology and typical risks (additionality, leakage, permanence, buffer, and reversal). Source: OECD (2022).

In contracts, the issue is allocating risk where it can be managed. Useful clauses include: title and usage rights, representations and warranties on authorization and CA, notification obligations for regulatory changes in the host country, indemnities if double claiming emerges, and replacement mechanisms or price-adjustment mechanisms. Source: World Bank.

Traceability must be verifiable and archivable. Require an audit trail on recognized registries (national or UNFCCC, or interoperable ones) and transaction logs. For 6.4, also verify SOP and OMGE deductions in the “net delivered” calculation. Source: UNFCCC (technical papers/workshops).

Finally, greenwashing signals are often mismatches between the claim and the boundary. Examples: using credits for “net-zero” without a hierarchy (internal reductions first), over-claiming on Scope 3, lack of disclosure on limits and uncertainties, or non-authorized credits presented as “correspondingly adjusted.” Source: OECD (2024).

If you want one practical rule that sums it all up: in Article 6 of the Paris Agreement—ITMOs, corresponding adjustments, and the carbon market, you are not buying only “reductions.” You are also buying a set of usage rights and an accounting treatment that must stand up to public and private scrutiny.