Article 6 is where the Paris Agreement meets carbon markets. It lets countries work together on their climate targets, including by moving emission reductions from one country’s books to another’s. For most buyers it sits in the background, but it is changing what some carbon credits are labelled and what they can be used for.
This page is part of our Learn section. For how government and voluntary markets differ, read voluntary vs compliance markets.
What is Article 6?
The Paris Agreement was adopted by 196 parties in Paris on 12 December 2015 and entered into force on 4 November 2016Source 1. Each country sets its own target, called a nationally determined contribution (NDC). Article 6 is the part that covers cooperation toward those NDCsSource 3.
It has three tracks:
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| Track | What it does | What is transferred |
|---|---|---|
| Article 6.2 — cooperative approaches | Bilateral or multilateral deals between interested countries | ITMOs |
| Article 6.4 — the mechanism (PACM) | Operated centrally through the UNFCCC; credits reductions by public and private actors | A6.4ERs |
| Article 6.8 — non-market approaches | Cooperation on sustainable development and poverty eradication | Nothing; it does not involve trading |
Source: UNFCCCSource 3.
Article 6.2: country-to-country deals
Under Article 6.2, countries agree deals with each other and transfer internationally transferred mitigation outcomes, or ITMOs. The UN guidance for Article 6.2 says ITMOs must be:
- real, verified and additional
- measured in tonnes of CO₂ equivalent, or another metric the countries agree
- generated in respect of, or representing, mitigation from 2021 onwardSource 4
ITMOs can count toward the buying country’s NDC, or be authorised for uses other than an NDC, which the guidance calls “other international mitigation purposes”Source 4. Airline offsetting under CORSIA is the best-known example.
Article 6.4: the Paris Agreement Crediting Mechanism
Article 6.4 sets up a crediting mechanism, known as PACM, run by the UNFCCC secretariat under the authority of the countries that are party to the Paris Agreement. It is supervised by the Article 6.4 Supervisory BodySource 5.
It works much like a voluntary standard: projects are registered, results verified and credits, called A6.4ERs, issued in its registry. It succeeds the Kyoto Protocol’s Clean Development Mechanism, which issued credits called CERsSource 6. At COP29, countries agreed that afforestation and reforestation projects and programmes of activities could transition from the CDM, with requests due by 31 December 2025Source 3.
A host country can authorise A6.4ERs for use toward other countries’ targets or other international purposes, or leave them unauthorised as mitigation contribution unitsSource 3.
Corresponding adjustments and double counting
The key idea in Article 6 is that a tonne should count only once. Each country taking part applies corresponding adjustments to its emissions balance for the ITMOs it transfers or uses, so a transferred tonne is not also counted toward the selling country’s NDC. The guidance requires this to be done in a way that avoids double countingSource 4.
Why this matters for voluntary credits
A voluntary credit that is not authorised under Article 6 comes with no corresponding adjustment, so the host country may also count the same reduction toward its own target. Authorised credits do come with one. For CORSIA’s first phase, for example, Verra credits with vintages from 2021 onward need an “Article 6 Authorized – International mitigation purposes” labelSource 7.
What did COP29 decide?
At COP29 in Baku, countries adopted the remaining guidance needed to run Article 6. The UNFCCC calls it the end of a nine-year journey to fully operationalise Article 6Source 3. Decisions included:
- For 6.2: detailed rules on authorisation, first transfers, registries and reporting, with no further negotiation of the guidance until its review resumes in 2028
- For 6.4: standards on methodologies and removals, the mechanism registry, and the CDM transition
- For 6.8: an assessment of the first phase of its work programme (2023–24) and recommendations for the second (2025–26)Source 3
What Article 6 means for you as a buyer
If you buy credits to compensate for your own emissions, you don’t need Article 6 credits. But it helps to know what the labels mean:
- An authorised credit has been approved by the host country for use abroad, and comes with a corresponding adjustment.
- An unauthorised credit is still a verified tonne, but the host country may also count it toward its own target. Keep that in mind when you word any claim.
Reduce your own emissions first, then choose credits whose claims match what you plan to say. For the bigger picture, read our history of carbon markets.