A no-deal Brexit (also called a clean-break Brexit) was the potential withdrawal of the United Kingdom (UK) from the European Union (EU) without a withdrawal agreement. Under Article 50 of the Maastricht Treaty, the Treaties of the European Union would have ceased to apply once a withdrawal agreement was ratified or if the two years had passed since a member state had indicated its will to leave the European Union. The two-year period could have been extended by unanimous consent from all member states, including the member state that was wishing to leave the European Union.
Without such an agreement in place at the end of the period specified in Article 50, EU law and other agreements would have ceased to apply to the established interactions between the UK and the rest of the EU. Additionally, British interactions with non-EU countries that had been governed by EU agreements with those countries may have needed to be renegotiated, as well.
Short-term (90-day) cross-border travel for tourism was expected to continue as before, albeit with some inconvenience to aviation schedules. While trading of goods (though not services) could have continued to operate under World Trade Organization (WTO) most favoured nation rules, some significant disruption to established trade flows was anticipated and the UK and the EU had prepared agreements and (short-term) understandings for the more serious risks anticipated to arise. Operation Yellowhammer was the codename used by HM Treasury for cross-government civil contingency planning for the possibility of a no-deal Brexit.
A renegotiated withdrawal agreement was ratified by Parliament in January 2020, and Brexit occurred at 23:00 GMT on 31 January 2020 (00:00 CET on 1 February). A Brexit transition period began at that point, to allow the sides to negotiate a trade agreement and to give time for the sides to prepare for the consequences of that agreement.
On 24 December 2020, the President of the European Commission and the Prime Minister of the UK agreed in principle to a draft EU–UK Trade and Cooperation Agreement. The Parliament of the United Kingdom ratified this agreement on 30 December 2020 and the European Parliament ratified it in late April 2021. The EU and UK agreed to apply the draft agreement with effect from 1 January 2021.
Events of 2019
In May 2019, the Speaker of the House of Commons advised that while a no-deal exit on 31 October 2019 was the current default position in law, it was not credible that Parliament could be deprived of the right to intervene should it wish to do so.
In July 2019 Boris Johnson became Prime Minister of the United Kingdom and Leader of the Conservative Party. The Department for Exiting the European Union, which had previously been responsible for Brexit negotiations, was refocused to concentrate on no-deal planning, with an additional £1 billion in funding for preparations for a no-deal Brexit. Johnson appointed Michael Gove to the Cabinet with the responsibility for co-ordination of planning across Government Departments for a no-deal Brexit, declaring that Gove would "turbo-charge" the UK's preparations for a no-deal Brexit on 31 October.
In August 2019, The Guardian reported that British diplomats would pull out from the EU's decision making meetings "within days", under plans being drawn up by Downing Street. That newspaper also said in the same month that any attempt to bypass MPs could create a constitutional crisis. On 21 August 2019, Angela Merkel offered and Boris Johnson accepted a suggestion that the British Government should come up with a viable alternative to the backstop, and on the same day the President of France Emmanuel Macron indicated that no deal was the most likely Brexit outcome due to the inability of the UK to accept the withdrawal agreement. At an interview with the BBC at the 45th G7 summit in late August 2019 Johnson suggested that the chances of achieving a Brexit deal were now "touch and go". He had previously stated that the odds of a no-deal exit were "a million to one". On 28 August 2019, the Johnson ministry reopened negotiations on the withdrawal agreement, but set as a pre-condition that the Irish backstop must be scrapped before doing so, a condition to which the EU had declared it would not agree.
On 30 October 2019, the day named as "exit day" in British legislation was changed to 31 January 2020 at 11.00 pm.