JI is set out in Article 6 of the Kyoto Protocol. JI projects can only be implemented in countries included in Annex I with a commitment described in Annex B. Such countries are usually industrialized countries of the OECD and Eastern Europe.

The Host Country has to be in compliance with the following eligibility requirements:

1. It is a Party to the Kyoto Protocol.
2. Its assigned amount of national GHG emissions has been calculated and recorded.
3. It has in place a system for the estimation of anthropogenic emissions by sources and anthropogenic removals by sinks of all greenhouse gases not controlled by the Montreal Protocol.
4. It has in place a national greenhouse gas registry. 
5. It has submitted annually the most recent required greenhouse gas inventory. 
6. It submits the supplementary information on assigned national GHG emissions.

A developed country has to fulfill at least criteria 1, 2 and 4 to be a potential Host Country for JI projects.

If a Host Country only fulfills criteria 1, 2 and 4 the project has to be implemented according to the "Track 2"-procedure, which is very similar to CDM.

JI projects are eligible since 2008.