Corresponding adjustment

A corresponding adjustment is the bookkeeping step that ensures an emission reduction counted toward one country's climate target is not also counted by another. When a country authorizes the international transfer of a mitigation outcome (known as an ITMO, or Internationally Transferred Mitigation Outcome), the transferring country must add the transferred tonnes back to its own greenhouse-gas inventory or subtract them from its Nationally Determined Contribution (NDC) accounting, while the acquiring country deducts them from its own balance. The net effect is that each tonne of CO₂-equivalent counts exactly once toward global mitigation.

The concept is established in Article 6.2 of the Paris Agreement (2015) and was operationalized through the Article 6 rulebook adopted at COP26 in Glasgow (2021) and refined at COP27 and COP28. It applies both to cooperative approaches under Article 6.2 (bilateral or plurilateral deals) and to credits issued under the Article 6.4 mechanism, where the host country must decide whether to "authorize" a credit for international use — triggering the adjustment — or keep it for domestic use.

Key features:

• Adjustments are tracked in annual and biennial reports submitted to the UNFCCC secretariat.
• They cover only authorized ITMOs; voluntary carbon market credits not authorized by the host government generally do not receive a corresponding adjustment.
• The rules apply to both single-year and multi-year NDC targets, with averaging methods for the former.

The mechanism is politically sensitive because it forces host countries — often developing nations selling credits — to forgo using those reductions toward their own NDCs. Switzerland's bilateral deals with Ghana, Peru, and others were among the first real-world tests of how corresponding adjustments work in practice.