Corresponding adjustments explained: the Article 6 rule behind carbon credit claims

Corresponding adjustments are the carbon market accounting rule that stops one emissions reduction being counted twice. They do not prove a carbon credit is high quality, but they can decide whether an international claim is even possible.

The carbon market has a deceptively simple promise: one credit should represent one tonne of emissions reduction or removal. The harder question is who gets to count that tonne.

If a project in one country reduces emissions and a buyer in another country wants to use that reduction, the same tonne can easily appear in two places: the host country's climate target and the buyer's claim. Corresponding adjustments exist to stop that from happening.

That is why the term matters well beyond climate diplomacy. It affects Article 6 carbon market transfers, CORSIA aviation offsetting, voluntary corporate claims and the price gap between ordinary carbon credits and units with stronger international accounting evidence.

Quick answer

A corresponding adjustment is an accounting adjustment made under Article 6 of the Paris Agreement when a mitigation outcome is authorised for international use. In plain English, the host country adjusts its climate accounting so the same emissions reduction is not also counted toward its own Nationally Determined Contribution (NDC).

The simple accounting problem

Imagine a clean-cooking project in Country A reduces emissions by 100,000 tonnes of carbon dioxide equivalent. Country B buys the mitigation outcome and wants to use it toward its own climate target. A corporate buyer may also want to use a unit from the project for a public climate claim.

If Country A also counts the same 100,000 tonnes toward its own NDC, global accounting has inflated progress. The emissions reduction happened once, but it has been counted twice.

A corresponding adjustment is the accounting response. The host country gives up the right to count the transferred mitigation outcome toward its own target, so the acquiring country or authorised user can count it without creating the same double claim.

This is why corresponding adjustments are sometimes described as the backbone of Article 6. They do not create the emissions reduction. They decide how that reduction is allocated in national climate accounts.

Article 6.2 and ITMOs

Article 6.2 covers cooperative approaches between countries. The units or outcomes transferred under this route are called Internationally Transferred Mitigation Outcomes (ITMOs). They can come from bilateral or multilateral arrangements, and they are more flexible than a single centralised crediting system.

The flexibility is useful, but it makes accounting discipline more important. Countries can design different cooperation models, but they still need authorisation, tracking, reporting and corresponding adjustments so transferred outcomes are not used twice.

For a buyer or analyst, the key distinction is between a signed cooperation agreement and a completed, evidenced transfer. A memorandum, framework agreement or project announcement can signal future supply. It does not by itself prove that an ITMO has been authorised, transferred, adjusted and recorded.

Article 6.4 and authorised units

Article 6.4 is the central United Nations Framework Convention on Climate Change (UNFCCC) supervised crediting route, now known as the Paris Agreement Crediting Mechanism (PACM). It can issue Article 6.4 emission reductions, but not every Article 6.4 unit carries the same claim value.

This distinction matters because "Article 6.4" is not enough as a buyer answer. The next question is authorised for what use, by whom, in which registry record, with what adjustment and for what claim.

Why CORSIA makes the issue practical

CORSIA is the aviation offsetting framework run through the International Civil Aviation Organization (ICAO). Airlines cannot use any carbon credit they like. They need eligible emissions units that fit CORSIA's programme, vintage, scope and accounting rules.

That is where corresponding adjustments become operational rather than theoretical. For relevant CORSIA use, a buyer may need a Letter of Authorisation or equivalent host-country evidence showing that the unit is authorised for international aviation use and that the national accounting treatment will prevent double counting.

For airlines, brokers and project developers, the commercial point is simple: a credit can be useful in the voluntary market and still fail a CORSIA eligibility test if the authorisation and accounting evidence are missing. For the market, this can create a premium for units with cleaner documentation.

What buyers should ask for

A corresponding adjustment is only useful if it can be evidenced. Buyers should not rely on broad language such as "Paris aligned", "Article 6 ready" or "authorised soon" without seeing the document trail.

The practical workflow is to define the intended claim first, then ask which evidence that claim needs. A buyer making a climate contribution claim may need a different file from an airline buying for CORSIA, a country using ITMOs toward an NDC, or a company making an international offsetting claim.

What a corresponding adjustment does not prove

The most common mistake is treating a corresponding adjustment as a full quality verdict. It is not. It answers one important question: whether the same mitigation outcome is being counted in two climate accounts. It does not answer every question about the underlying credit.

That is the right way to read the evidence. Corresponding adjustments make some international uses possible. They do not turn a weak project into a strong one, and they do not remove the need for ordinary carbon credit due diligence.

Where claims can go wrong

The first risk is a missing adjustment. A buyer may assume that a voluntary credit has Paris Agreement accounting attached because the project is in a country with an NDC. That assumption is not enough. The host country needs to authorise the use and apply the relevant accounting treatment where the claim requires it.

The second risk is the wrong claim. A mitigation contribution unit may be a reasonable way to support climate finance, but it should not be described as if it neutralises another party's emissions in the same way as an authorised, adjusted unit.

The third risk is timing. Authorisation, transfer, retirement and national reporting may not happen at the same moment. A buyer should understand whether the evidence exists now, is scheduled later or is merely expected.

The fourth risk is using one evidence layer to hide another weakness. A corresponding adjustment can reduce double-counting risk, but if the baseline is fragile, permanence is weak or the claim exaggerates the result, the buyer still has a problem.

How to read the market signal

Corresponding adjustments are likely to become one of the dividing lines in carbon credit pricing. Credits with clearer host-country authorisation and registry evidence may be more valuable to buyers that need CORSIA compliance, Article 6 transfer evidence or stronger public-claim support.

That does not mean every buyer should chase adjusted units. Some companies may decide that contribution claims, direct decarbonisation, supplier work or removals procurement better fit their strategy. The useful shift is clarity. Buyers can no longer treat every tonne as interchangeable once national accounting and claim use are part of the decision.

The market is moving from a generic question, "is this a carbon credit?", toward a more useful one: "what can this specific unit credibly support?"

FAQ

What is a corresponding adjustment in simple terms?

It is the accounting change that stops a transferred emissions reduction being counted twice. The host country adjusts its climate accounting so another country or authorised user can count the mitigation outcome for the agreed purpose.

Is a corresponding adjustment the same as a carbon credit?

No. A carbon credit or mitigation outcome is the unit. A corresponding adjustment is the accounting treatment attached to an authorised international use of that unit.

Do voluntary carbon credits need corresponding adjustments?

Not always. It depends on the claim and use. Some voluntary contribution claims may not require an Article 6 corresponding adjustment, but CORSIA, country transfers and some international offsetting claims may require stronger host-country authorisation and accounting evidence.

Does Article 6 make a credit high quality?

No. Article 6 accounting can address double counting, but buyers still need to check additionality, permanence, leakage, safeguards, methodology, registry records and claim wording.

What should a buyer ask a broker first?

Ask whether the unit is authorised for the intended use, whether a corresponding adjustment applies, where that is recorded, which registry identifiers prove the unit status, and what claim the evidence can safely support.

Useful source links

• UNFCCC: Article 6 of the Paris Agreement
• UNFCCC: Article 6.2 cooperative approaches
• UNFCCC: Paris Agreement Crediting Mechanism
• UNFCCC: Article 6.4 PACM registry
• ICAO: CORSIA eligible emissions units
• Article 6 Implementation Partnership: current developments