How do countries join the EU?

Any ‘European’ country who fulfils the EU criteria of membership can apply to join the EU. Membership criteria are known as the Copenhagen criteria. These include ‘a free-market economy, a stable democracy and the rule of law, and the acceptance of all EU legislation.

A country wishing to join the EU submits a membership application to the European Council, which asks the European Commission to assess whether the applicant can meet the Copenhagen criteria. If the Commission thinks so, the European Council agrees on a framework for negotiations with the candidate country. Membership negotiations cannot start until all EU governments agree.

Negotiations encompass 35 policy areas, known as chapters, covering all current EU legislation. Not all chapters are opened at the same time and the speed of negotiations depends on how quickly the candidate country can adopt EU legislation and fulfill the benchmark conditions set out by the EU. No negotiations on a chapter can be closed until every EU government is satisfied. The negotiation process is only concluded once every chapter has been closed.

Once negotiations are complete, the candidate country signs an an Accession treaty, setting out when it will formally join the EU. This treaty has to be approved by all governments, the European Commission and the European Parliament. Each EU member state also has to ratify the treaty.

Find out more – read our explainer on the various EU institutions.

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