On 2016-06-23, the UK held a nationwide referendum on EU membership. Voters chose to leave the EU, setting off a multi-year political and legal process about how, and on what terms, withdrawal would happen.
On 2017-01-24, the UK Supreme Court ruled that the government could not trigger Article 50 using executive powers alone. An Act of Parliament was required because withdrawal would remove legal rights created in UK law through EU membership.
On 2017-03-16, the European Union (Notification of Withdrawal) Act 2017 became law. It gave the Prime Minister authority to notify the EU of the UK’s intention to withdraw under Article 50.
On 2017-03-29, Prime Minister Theresa May notified the European Council that the UK intended to leave the EU. This started the Article 50 process and began formal negotiations over an orderly withdrawal.
On 2018-06-26, the European Union (Withdrawal) Act 2018 became law. It set a domestic legal framework for leaving the EU, including repealing the European Communities Act 1972 on “exit day” and creating “retained EU law” to avoid legal gaps.
In November 2018, negotiators reached agreement in principle on a draft Withdrawal Agreement text. The draft covered issues such as citizens’ rights, the financial settlement, and arrangements to prevent a hard border on the island of Ireland.
On 2018-11-25, EU leaders endorsed the Withdrawal Agreement and a Political Declaration on the future relationship. This moved the process from negotiating text to winning political and parliamentary approval.
On 2019-01-15, the House of Commons rejected the government’s Withdrawal Agreement in the first major approval vote required by UK law. The defeat deepened political deadlock and increased the risk of leaving without an agreement.
On 2019-03-12, MPs rejected the deal a second time. On 2019-03-13, MPs then voted to reject leaving the EU without a deal (though the vote was not legally binding), signaling a desire to avoid an abrupt break.
On 2019-04-10, EU leaders agreed to extend the Article 50 period until 2019-10-31 at the latest. The extension aimed to reduce the immediate risk of a no-deal exit while the UK tried to break its domestic political stalemate.
On 2019-05-24, Prime Minister Theresa May announced she would resign as leader of the Conservative Party, after repeated failures to secure parliamentary approval for her Brexit deal. Her resignation opened the way for a new leader with a different approach to negotiations.
On 2019-07-24, Boris Johnson became Prime Minister, promising to leave the EU by 2019-10-31. The change in leadership reset UK negotiating tactics and intensified the near-term risk of a no-deal outcome.
On 2019-09-09, the European Union (Withdrawal) (No. 2) Act 2019 (the “Benn Act”) became law. It required the Prime Minister to request an extension if Parliament had not approved a deal or approved no-deal by a specified deadline, aiming to block no-deal exit on 2019-10-31.
On 2019-10-17, the UK and EU agreed a revised Withdrawal Agreement, including new arrangements on Ireland/Northern Ireland (the Protocol). The revision was designed to address objections to the earlier “backstop” and to enable ratification.
On 2019-10-29, the European Council adopted a decision extending the Article 50 period to 2020-01-31. This provided time to complete domestic approvals and ratify the revised agreement, and it reduced immediate no-deal risk.
On 2019-12-12, the UK general election gave the Conservative Party a clear House of Commons majority. This changed the parliamentary arithmetic and made ratification of the revised Withdrawal Agreement much more likely.
On 2019-12-19, MPs passed the second reading of the Withdrawal Agreement Bill, the domestic law needed to implement the deal. This marked a major step from negotiation to final legal implementation.
On 2020-01-23, the European Union (Withdrawal Agreement) Act 2020 received Royal Assent. This legislation put the Withdrawal Agreement into UK law, enabling the UK to leave the EU with a negotiated exit.
On 2020-01-24, the EU and UK signed the Withdrawal Agreement. Signing signaled that both sides had settled the withdrawal terms and were completing final ratification steps before the exit date.
At 23:00 GMT on 2020-01-31, the UK ceased to be an EU member state and the Withdrawal Agreement entered into force. A transition period then began, keeping most rules temporarily in place while the UK and EU prepared for their next-stage relationship.
Brexit: Referendum, Negotiation, and Withdrawal (2016-2020)