[Euro Facts] Article 49: rejoining the EU | Institute of Government

“Article 49 of the Treaty on European Union establishes how a country can join the EU. As the UK left the EU on the 31 January 2020, it is now considered a third country under EU law. If it wanted to rejoin the EU one day, the UK would join through the framework set out by Article 49.”

https://www.instituteforgovernment.org.uk/explainers/article-49-rejoining-eu