Brexit “happened” in stages, but the key date most people mean is 31 January 2020, when the United Kingdom formally left the European Union at 23:00 GMT.

Key Brexit dates

  • 23 June 2016 – Brexit referendum: the UK voted to leave the EU, with 51.9% for Leave and 48.1% for Remain.
  • 29 March 2017 – Article 50 triggered: the UK formally notified the EU of its intention to leave, starting a two‑year negotiation period.
  • 31 January 2020 – Exit day: the UK officially withdrew from the EU and entered a transition period.
  • 31 December 2020 – End of transition: EU rules stopped applying in most areas, and the new UK‑EU relationship began.

In everyday conversation, when people ask “when did Brexit happen,” they usually mean the formal exit on 31 January 2020, even though the political and legal process stretched from the 2016 referendum through the end of the 2020 transition period.

Information gathered from public forums or data available on the internet and portrayed here.