 All new EU members having joined the bloc after the signing of the Maastricht Treaty in 1992 are obliged to adopt the euro under the terms of their accession treaties.However, the last of the five economic convergence criteria, which need to be complied with in order to qualify for euro adoption, is the exchange rate stability criterion.This requires having been a member of the ERM for a minimum of two years without the presence of "severe tensions" for the currency exchange rate.