Corresponding Adjustments Made Simple: Authorisation and Claims

Why the same tonne can be counted twice, how host-country authorisation and corresponding adjustments prevent it, and what that means when you buy for CORSIA or a voluntary claim.

Some listings and buyer requirements mention "authorisation" or a "corresponding adjustment". These two words now separate credits that can be used for CORSIA from those that cannot, and they increasingly affect the price and the claims a company can make. This page explains the idea without the treaty language, then covers the practical checks.

The problem: one tonne, two owners

Under the Paris Agreement, every country sets a national climate target, called its Nationally Determined Contribution (NDC). Each country reports its emissions against that target.

Now imagine a biogas project in Gujarat. It cuts methane, and that cut shows up in India's national inventory, helping India meet its target. If the project also sells a credit for the same tonne to an airline in Europe, and the airline counts it towards its own offsetting obligation, the tonne has been used twice: once by India and once by the airline. The atmosphere only benefited once.

That is double counting, or more precisely, double claiming.

The fix: a corresponding adjustment

Article 6 of the Paris Agreement lets countries transfer emission reductions to one another, or to other uses such as CORSIA, as long as the books balance. When a host country agrees that a tonne will be used outside its own target, it makes a corresponding adjustment: it adds that tonne back to its reported emissions, as if the reduction had not happened for national purposes. The tonne now belongs to one claimant only.

Before any adjustment, the host country gives a formal authorisation for the units. In practice, authorisation is a letter or decision from the government's designated authority stating that specific units from a specific project may be used for a stated purpose. The adjustment itself is then applied in the country's reporting to the UNFCCC.

Credits that are authorised and adjusted are often described as Article 6 units or, in the Paris text, internationally transferred mitigation outcomes (ITMOs).

Why it matters for CORSIA

For the current CORSIA compliance periods, eligible emissions units need a host-country authorisation and must be backed by a corresponding adjustment. An airline cancelling units without this support risks having them rejected by its national authority, which in India is the DGCA.

So for an airline buyer, the authorisation is not optional. It is part of eligibility, together with the programme, the vintage window and the registry record. Our CORSIA eligible units checklist sets out all the conditions together.

Why it matters for voluntary buyers

A company buying credits for its own climate goal does not strictly need a corresponding adjustment. Many voluntary buyers purchase non-authorised credits and describe them as a contribution to climate action in the host country, rather than as a direct offset of their own emissions.

Others want authorised units so they can make a stronger offsetting claim without the double-claiming question hanging over it. Either is defensible if the wording matches the unit. Our guide to claims after retiring credits has suggested language for each case.

India's position, in brief

India has published a list of activity types it is prepared to consider for authorisation under Article 6, and it is developing the rules that link this to its domestic Carbon Credit Trading Scheme. The details are still evolving, and authorisation is decided case by case. We do not publish a list of approved activities here because it changes. Sellers should check the current position with the national authority before promising authorised units to anyone.

Practical checks before you buy

What to ask	What a good answer looks like
Is the lot authorised?	Yes, with a copy of the host-country authorisation naming the project and the use
For which use?	The stated purpose covers your need, for example international mitigation purposes including CORSIA
Which vintages and quantities?	The authorisation covers the vintage and volume you are buying
Has the adjustment been applied?	The seller can show how it will be or has been reflected, and the registry marks the units accordingly where it supports this
What if authorisation is withdrawn or delayed?	The contract addresses it, especially for Forward lots

Many registries now label units that carry an authorisation, which makes it easier to check. If the seller only offers a verbal assurance, treat the lot as non-authorised until shown otherwise.

For sellers

If you are a developer hoping to sell to airlines, authorisation is likely the most important document you can obtain. When you register a project on our seller intake form, you record its authorisation status once, and buyers filtering for CORSIA-ready supply can see it. Our CORSIA services include help with host-State authorisation and corresponding adjustments.

Whether you are buying authorised units or hoping to sell them, we can go through the paperwork for a specific lot with you. Start with a note through the contact page.