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Registry Systems under the Kyoto Protocol
Related information

 FCCC/SBSTA/2005/INF.3
Checks to be performed by the International Transaction Log Data Exchange Standards
(DES) Technical Specification

Related decisions

Decision 13/CMP.1 on assigned amount accounting under the Kyoto Protocol
Decision 3/CMP.1 on guidelines for the CDM (Appendix D on CDM registry)
Decision 5/CMP.1 on afforestation and reforestation CDM project activities

Update 12 December 2025:
Information on the implications of the cessation of operations of the international transaction log (ITL), scheduled for 31 March 2026

Background

In its decision “Guidance relating to registry systems under Article 7, paragraph 4, of the Kyoto Protocol”, the CMP requested the secretariat to publish, on the UNFCCC website, information on the implications of the cessation of operations of the international transaction log (ITL), scheduled for 31 March 2026.

Status of national registries

  • All issuances of AAUs, RMUs, and ERUs by national registries have been completed. No further issuance of such units is possible.
  • All national registries have also finalized their retirements, and all Annex I Parties under the Kyoto Protocol are in compliance with their QELRC. Consequently, no further retirement transactions are allowed.
  • Following the completion of the true-up period for the second commitment period on 9 September 2023, national registries can no longer transfer or acquire Kyoto Protocol units between themselves (i.e. international transfers).
  • Internal transfers between holding accounts within a registry and the cancellation of Kyoto Protocol units remain possible.
  • A limited number of residual forwards of CERs from the CDM registry may still occur (four forwards took place in the past year). Such forwards will remain possible until a national registry is disconnected from the ITL (no later than 31 March 2026).
  • Reporting on transactions to and from national registries is no longer required.
  • Each Party maintaining a registry connected to the ITL may opt to disconnect its registry and subsequently close its registry prior to 31 March 2026. 

Status of the CDM registry 

  • The CDM registry will be disconnected from the ITL at the end of March 2026. Its functions of issuance and cancellation of xCERs will continue independently after March 2026, until 31 Decembre 2026.
  • As of the end of March 2026, the CDM registry will cease forwarding xCERs to national registries.

Transfers between holding accounts in a national registry after disconnection

The ability of a national registry to continue transferring Kyoto Protocol units between holding accounts after it is disconnected from the ITL (no later than March 2026) depends on its specific implementation - particularly how it handles transfers between accounts of the same type (e.g., 100 or 120 accounts).

In general, once a registry is disconnected from the ITL, and unless its source code and/or configuration is modified, it is reasonable to assume that it will be unable to process transactions involving Kyoto Protocol units because the ITL will no longer be available to validate such transactions.

An exception may exist for internal transfers between two accounts of the same type, if the registry software was designed to allow such transfers without ITL validation.

Cancellations after disconnection 

Similarly, a registry that has been disconnected from the ITL (no later than March 2026) and that has not been updated or reconfigured will be unable to complete cancellations of Kyoto Protocol units because the ITL validation required for such transactions will no longer be accessible.

Forwards of CERs from the CDM registry after disconnection

Once a national registry is disconnected from the ITL (no later than March 2026), it will no longer be able to receive forwarded CERs from the CDM registry.

Emission targets for industrialized country Parties to the Kyoto Protocol are expressed as levels of allowed emissions, or "assigned amounts", over the 2008-2012 commitment period. Such assigned amounts are denominated in tonnes (of CO2 equivalent emissions) known informally as "Kyoto units".

The ability of Parties to add to their holdings of Kyoto units (e.g. through credits for CDM or LULUCF activities) or move units from one country to another (e.g. through emissions trading or JI projects) requires registry systems that can track the location of Kyoto units at all times.

Two types of registry have been implemented:

  • Governments of the 38 Annex B Parties have implemented national registries, containing accounts within which units are held in the name of the government or in the name of legal entities authorized by the government to hold and trade units.
  • The UNFCCC secretariat, under the authority of the CDM Executive Board, has implemented the CDM registry for issuing CDM credits and distributing them to national registries. Accounts in the CDM registry are held only by CDM project participants, as the registry does not accept emissions trading between accounts.

In addition to recording the holdings of Kyoto units, these registries "settle" emissions trades by delivering units from the accounts of sellers to those of buyers, thus forming the backbone infrastructure for the carbon market.

Each registry operates through a link established with the International Transaction Log (ITL) put in place and administered by the UNFCCC secretariat. The ITL verifies registry transactions, in real time, to ensure they are consistent with rules agreed under the Kyoto Protocol. The ITL requires registries to terminate transactions they propose that are found to infringe upon the Kyoto rules.

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In verifying registry transactions, the ITL performs an independent check that unit holdings are being recorded accurately in registries. After the Kyoto commitment period is finished, the end status of the unit holdings for each Annex B Party will be compared with the Party emissions over the commitment period in order to assess whether it has complied with its emission target under the Kyoto Protocol.

EU emissions trading

Domestic or regional emissions trading schemes that use Kyoto units also undertake their settlement through these registry systems. For example, under the second phase of the  EU. The EU Emissions Trading System (EU ETS) allowances are specific Kyoto units which have been designated as being valid for trading under the scheme. Transactions in the EU allowances are therefore recorded automatically as transactions under the Kyoto Protocol.

As EU trading legislation sets in place rules over and above those agreed for the Kyoto Protocol, a supplementary transaction log has been implemented by the European Commission. The European Union Transaction Log (EUTL) previously Community Independent Transaction Log, has been in place since the start of the scheme in 2005 and EU registries are now operating with it.

For the start of the Kyoto commitment period in 2008, EU registries are to switch their connections from the EUTL to the ITL. The ITL will conduct 'Kyoto checks' on transactions proposed by both EU and non-EU registries. In the case of transactions involving EU registries, the ITL will forward information to the EUTL so that it can conduct 'supplementary checks' defined under the EU scheme.

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