Installations and airlines are allowed to use CERs and ERUs from Kyoto Protocol projects (CDM or JI) for compliance in the EU ETS.  The number of Kyoto credits which can be used depends on the rules of different member states.  In Phase II, this varies mainly between 0% - 22% of the allocation across the EU for stationary installations and it is a fixed 15 % of the verified emissions for the aircraft operators.

In Phase III, stationary installations can also use Kyoto credits.  The number that can be used in Phase III is (A) the higher of (i) the number which could be used in Phase II and (ii) 11% of the total allocation in Phase II (B) less the number if Kyoto credits actually used for compliances in Phase II. Aircraft operators also shall be able to use credits up to an amount corresponding to a percentage, which shall not be set below 1.5 %, of their verified emissions during the period from 2013 to 2020.