Yes, legally it can. The EU treaties say that a country that has left and wants to come back must apply like any other candidate, under Article 49 of the Treaty on European Union, which requires the unanimous agreement of all member states and the consent of the European Parliament.
The treaties answer the legal question directly. Article 50 of the Treaty on European Union, the article the United Kingdom used to leave, ends with this sentence: “If a State which has withdrawn from the Union asks to rejoin, its request shall be subject to the procedure referred to in Article 49.” There is no special fast track. A returning country is treated like any new applicant.
Article 49 sets out that procedure. Any European state that respects the EU’s values may apply. The application is sent to the Council of the EU, and the European Parliament and national parliaments are informed. In practice, the Commission gives an opinion, and the European Council decides unanimously to grant candidate status and then to open negotiations. Negotiations cover more than 30 policy chapters of EU law. At the end, the Council must agree unanimously, the European Parliament must give its consent by a majority of its members, and an accession treaty must be ratified by every member state and by the applicant, through parliamentary votes or referendums depending on each country’s constitution.
An applicant must also meet the Copenhagen criteria, set by the European Council in 1993: stable democratic institutions and the rule of law, a functioning market economy, and the ability to take on all the obligations of membership.
Example
The terms of the UK’s former membership would not automatically return. While a member, the UK had special arrangements: for example, it had notified that it would not take part in the single currency. The treaties provide no guarantee that such arrangements would be offered again; they would be part of any new negotiation.
Debates and limits
As of 1 November 2026, the UK has not applied. The Labour government elected in 2024 has ruled out a return to the single market, the customs union or free movement, while seeking a closer partnership: the first EU-UK summit, on 19 May 2025, launched a new strategic partnership, including a security and defence partnership. Supporters of rejoining argue that membership would bring economic and political benefits; opponents argue that it would reverse the 2016 vote and bring back obligations the UK chose to leave. Whether, when and on what terms the UK might apply again is a political question for British voters and governments, and then for the 27 member states.