This article is updated regularly as events unfold.
On April 11 European leaders agreed to extend the UK's EU membership until October 31, following a second request by the British government for a delay to Brexit.
The United Kingdom is due to leave the European Union — an economic and political partnership of 28 countries — bringing to an end 46 years of British membership.
Brexit is set to be the most important constitutional shake-up the UK has known since it joined the six-nation European Economic Community in 1973, and represents the first time the European institution has lost a member.
The process has plunged the UK into its worst political and constitutional crisis since the Second World War. The country had been due to leave the EU on March 29, 2019, but the revised departure date is now October 31 after gridlock in parliament twice forced the government to seek a delay.
The House of Commons has rejected a divorce deal three times but has been unable to agree on an alternative path. The Withdrawal Agreement on the terms of the UK’s exit, and a Political Declaration outlining a framework for future ties, had been negotiated by London and Brussels and approved by the 27 other EU governments.
The UK voted to leave the EU by 52% to 48% in a June 2016 referendum. The result has increased strains between the UK's individual countries: England (53%) and Wales (52.5%) voted to leave, whereas Scotland and Northern Ireland voted by 62% and 56% respectively to remain in the EU.
The latest developments (to May 15):
May 2019: UK to hold EU poll three years after vote to leave
The parliamentary deadlock on Brexit means the UK remains in the EU for now and will take part in this month's European Parliament elections, holding the vote on May 23.
Meanwhile cross-party talks have continued between the UK’s ruling Conservatives and Labour opposition. They are aimed at securing a compromise deal on the country's departure and future relations with the bloc, capable of winning the support of a majority of MPs. But so far there has been no sign of a breakthrough.
The thrice-defeated Brexit deal will come back before parliament in the first week of June, the government has said. MPs will not hold a fourth vote on the Withdrawal Agreement itself, but on key legislation needed to put the UK's departure from the EU into effect.
Britain’s two main parties are both reeling from local elections on May 2 at which they paid the price for the stalemate, and are forecast to suffer badly at the European poll. Support has surged for a new Brexit Party, which advocates leaving the EU without a formal agreement.
But in a sign that opinion in the UK is becoming still more polarised, pro-EU parties are also attracting support collectively — although surveys suggest their share of the vote may be split.
Reports have suggested that the prime minister might use the cross-party talks to move towards a "softer Brexit", involving a temporary customs arrangement with the EU. Labour has argued for a permanent customs union.
But both Theresa May and Jeremy Corbyn face a huge challenge in reconciling any compromise with their own parties, both inside and outside parliament.
Conservatives are furious at the failure to “deliver Brexit”. Many of the party’s grassroots, who already viewed the deal negotiated with the EU as a sell-out, have become openly insurgent against May's leadership. For them, a customs union would deny the UK an independent trade policy, a red line for many “Leave” supporters.
Labour — accused of sitting on the fence over Brexit — has sought to ensure any deal cannot be ditched by May’s successor. However, it has its own huge dilemmas. A membership overwhelmingly pro-EU and in favour of a second referendum would be furious if Corbyn played the midwife who delivered a “Tory Brexit”. Yet key senior party figures are loath to aggravate further their traditional working-class supporters, many of whom are pro-Leave.
With little reported progress in the talks apart from in areas such as workers’ rights and environmental standards, there are calls on both sides for them to be abandoned.
The danger faced by both leaderships is that to cede ground on the key issues – the future trading relationship, a second public vote – may split their parties. Also, there is no guarantee that a compromise deal would be passed in parliament.
UK deadlock pushes Brexit date back to October
EU leaders met for a special European Council summit on April 10 and agreed to a six-month "flexible extension" to the UK's departure from the bloc, with a new date set for October 31.
The United Kingdom can leave earlier if its parliament approves the negotiated withdrawal deal, but the delay means the country is all but certain to take part in the vote to elect a new European Parliament.
The repeated defeats for the exit deal in the House of Commons had twice forced the British government to seek an extension. Many leaders wanted a longer delay but objections led by France resulted in a compromise.
The summit ended with an appeal to the UK from European Council President Donald Tusk not to "waste this time". EU leaders will review the situation at their regular summit in June.
The cross-party talks followed a shift in Theresa May's Brexit strategy, given the parliamentary gridlock. Previously focused on trying to win over eurosceptics in her Conservative Party and Northern Irish unionists, her government turned to the Labour opposition.
This year has seen parliament reinforce its opposition to a "no deal" Brexit, passing a law to seek a further delay if no deal is passed. However, two rounds of non-binding "indicative votes", designed to find alternative options to the negotiated UK-EU deal, failed to secure a majority of MPs in favour of any proposal.
The main opposition Labour Party has confirmed that its policy is to back a second referendum if the government doesn't change its Brexit deal or call a general election.
The heightened uncertainty in recent months has forced the UK and the EU, as well as people and businesses on both sides of the English Channel, to step up preparations for a no-deal Brexit.
Month of turmoil forces UK to seek Brexit delay – twice
- March 12: the EU withdrawal deal suffers a second resounding defeat by 149 votes in the House of Commons. In the first vote in January the government lost by a record margin of 230.
- March 13: MPs vote to reject a no-deal Brexit from happening under any circumstances. In one of the two votes, several government ministers defy orders to keep a no-deal option on the table.
March 14: MPs back the government to ask the EU to a delay Brexit until June 30, if parliament passes the exit deal.
March 18: House of Commons Speaker John Bercow rules out a third vote on the Brexit deal, barring substantial changes.
March 19: EU's chief Brexit negotiator Michel Barnier calls on the bloc to "finalise all preparations for a no-deal scenario".
March 21: EU leaders meet for a European Council summit and offer the UK two alternative Brexit extensions, both shorter than the UK's request: May 22 if the deal is passed, April 12 if it is not.
March 23: hundreds of thousands of pro-EU protesters march in London to demand a second referendum.
March 25: the European Commission says it is "increasingly likely" that the UK will leave the EU with no deal, and announces it has completed its "no-deal" preparations. UK MPs pass an amendment to a Brexit motion enabling them to seize control of the House of Commons agenda, paving the way for alternatives to the government's Brexit deal to be considered.
March 27: MPs hold a first round of "indicative votes" on a range of different Brexit models, but it fails to produce a majority for any. Prime Minister Theresa May says she is willing to step down if parliament passes her deal.
March 29: the House of Commons votes for a third time on the exit deal — but only on the Withdrawal Agreement, not the Political Declaration. It brings a third defeat for the government, this time by 58 votes.
March 31: a petition calling on the UK government to stop Brexit and remain in the EU, by revoking the formal process under Article 50, has now received more than six million signatures.
April 1: MPs hold more indicative votes but all four options are defeated.
April 2: after a long crisis meeting with her divided Cabinet, Theresa May says she will seek to work with Jeremy Corbyn to secure a compromise Brexit deal — a major shift in strategy which angers many Brexit supporters.
April 2: earlier in the day EU chief negotiator Michel Barnier warns "no deal" is increasingly likely, while French President Emmanuel Macron says the EU cannot be held "hostage" to the UK's "political crisis".
April 3: May holds talks with Corbyn who describes them a "useful but inconclusive". Two junior ministers quit in protest at May's strategy. MPs pass a bill from Labour's Yvette Cooper by just one vote to force the prime minister to seek a further delay to stop a no-deal Brexit.
April 4: Ireland's Prime Minister Leo Varadkar hosts Angela Merkel in Dublin. The German Chancellor pledges "major efforts to avoid a hard Brexit".
April 5: UK Prime Minister Theresa May requests another delay to Brexit, this time until June 30, opening up the possibility of Britain taking part in the European Parliament elections in late May.
April 6/7: May defends the compromise talks with Labour amid reports of scant progress. Eighty Labour MPs write to Corbyn to demand he insist on a second referendum.
April 9: May visits Merkel in Berlin and Macron in Paris. British MPs endorse her request to delay Brexit until the end of June. European Council President Donald Tusk invites EU leaders to consider a "flexible" extension of up to a year.
April 10/11: At a special European Council summit on Brexit, EU leaders approve a "flexible extension" of the UK's membership until October 31. It can be cut short if the withdrawal deal is passed. Otherwise, the UK retains full membership rights and obligations and will take part in European Parliament elections between May 23-26.
What happens in a 'no-deal scenario'?
In the absence of an alternative agreement, the default legal position is that the UK will leave the EU on the revised scheduled departure date of October 31.
In such a scenario, legal arrangements covering many aspects of everyday life would abruptly cease to apply. It would also bring a significant change in the trading relationship between the UK and the EU.
Many political leaders, institutions, companies and individuals have warned of severe disruption and economic damage — with the UK being hit worse than the EU.
However, Brexiteers have long dismissed “Project Fear” forecasts and some argue that the UK could survive perfectly well under World Trade Organisation (WTO) rules.
As the process dragged on without formal approval for an exit deal from the UK and EU parliaments, the focus shifted even more sharply to “no deal” preparations.
In April 2019, under two weeks before the UK's earlier scheduled departure date, a leaked letter by the government's most senior civil servant warned of an economic recession, food price rises, a severe impact on Britain's security services, police forces and legal system, and a return to direct rule by the UK government in Northern Ireland.
The UK government has published a series of papers advising citizens and businesses on the consequences and how to prepare for no-deal. It says the UK would become a "third country", and there would be no agreement on applying arrangements set out in the exit deal.
In March the European Commission said it had completed its no-deal preparations, having released its Contingency Action Plan for Brexit in December. In a no-deal scenario, it confirms that the rights of EU citizens living in the UK and Britons on the continent would no longer be protected at European level — and lays out basic plans to regulate financial services, air transport, road haulage, customs and exports, and climate policy.
In November 2018, two major reports by the UK Treasury and the Bank of England assessed the potential damage to the economy of various Brexit scenarios.
What does the Brexit divorce deal contain?
A successfully ratified deal would pave the way for an orderly UK exit from the European Union, quickly followed by full trade talks between the two sides — which were not allowed while Britain remained a member.
In November 2018 the British government and EU leaders approved a deal on the terms of the separation — the Withdrawal Agreement — and a political declaration on the nature of future EU-UK ties.
The near 600-page Withdrawal Agreement would be legally binding and settles the key “divorce” issues: the UK’s financial obligations to the EU, citizens' rights — those of EU citizens living in the UK and Britons living on the continent — and arrangements for the Irish border. Set to become the only land frontier between the UK and the EU, both sides agree this must remain open, but the historically sensitive and complex issue bedevilled the talks.
A ratified exit deal would also pave the way for a the way for a planned transition period to come into effect after the UK’s departure. During this period many existing arrangements would remain in place, allowing for more time to sort out future EU-UK relations and avoid an abrupt “cliff-edge” exit.
If no UK-EU trade deal was agreed by the end of December 2020 — although an extension to this period is possible under the draft accord — a "backstop" mechanism would come into force to keep the Irish border open. This would set up a basic UK-wide customs union with the EU, but with Northern Ireland more deeply integrated with the bloc's rules.
The Withdrawal Agreement was accompanied by a much shorter Political Declaration on future relations. This is not legally binding — but should form the basis for a trade agreement to be negotiated after Brexit.
Unlike Conservative Eurosceptics and Northern Irish unionists who have focused their hostility on the backstop arrangements in the Withdrawal Agreement, the UK's Labour Party has has emphasised its opposition to the Political Declaration. Leader Jeremy Corbyn has argued that the document is too vague and would lead the UK into a "blindfold Brexit".
Last-minute moves by Prime Minister Theresa May to seek a compromise deal with Corbyn have focused attention on Labour's demands for a customs union with the EU. Michel Barnier, the EU's chief Brexit negotiator, has said such an arrangement could be included in the Political Declaration.
Read more:Political Declaration: the details
Why has the UK parliament repeatedly rejected the deal?
Theresa May has insisted the deal is in the national interest and there is no viable alternative. She has argued that it delivers on the referendum result: an end to free movement, an end to huge UK payments to the EU, and an exit from the unpopular EU structures on farming and fishing.
However, the agreement brought hostility from both supporters and opponents of Brexit. In parliament, an alliance of forces resulted in the two historic defeats for the government.
The main Labour opposition said the deal did not meet its six Brexit tests, which include a customs union with the EU.
Derailed by the backstop
The controversial backstop, the mechanism in the agreement to guarantee an open border on the island of Ireland, proved to be a major stumbling block. The difficulty is that the frontier between Northern Ireland and the Republic of Ireland – one of the most politically sensitive borders in the world – will become an EU-UK land border after Brexit, yet the UK wishes to pursue an independent trade policy.
The backstop envisages the UK remaining in a "single customs territory" with the EU in the absence of a free trade deal, as a kind of insurance policy to keep the border open.
Eurosceptic critics suspect it will keep the UK strapped permanently to EU trade policy. EU sources pointed out that the UK-wide mechanism in the withdrawal agreement was included at the UK’s request, to avoid splitting off Northern Ireland from the rest of the UK.
Northern Ireland's Democratic Unionist Party (DUP), on whose support the government depends, has vehemently opposed any move they believe might separate Northern Ireland from the rest of the United Kingdom. Under the backstop, as set out in the deal, Northern Ireland would stay aligned to some EU rules.
On March 11 the UK and the EU said they had agreed a revised Brexit deal, following weeks of deadlocked talks between London and Brussels. The British parliament had voted to seek “alternative arrangements” for the backstop after the first parliamentary defeat.
EU27 leaders had refused to alter the text of the withdrawal agreement. But British Prime Minister Theresa May said she had secured legally-binding changes over the backstop’s application. European Commission President Jean-Claude Juncker said “meaningful legal assurances” had been given — while warning that there would be "no third chance" to revise the deal again.
However, leading members of the Conservative anti-EU European Research Group (ERG) and the DUP rejected the new proposals, after consulting new legal opinion on the deal from the government's top lawyer. The deal suffered a second defeat on March 12.
The government decided the third vote in the House of Commons on March 29 would be only on the withdrawal deal, not on the declaration on future relations. This was partly to conform to a ruling by the Speaker who insisted on substantial changes from the previous vote. However, it still ended in defeat by 58 votes.
The parliamentary deadlock prompted moves by MPs from different parties to wrest control of the Brexit process and allow a series of "indicative votes" to explore alternative solutions to the government's deal. So far there has been no majority for any particular solution, other than an opposition to no-deal.
How did Brexit get into such a mess?
Recent months have seen turmoil in the British domestic political scene. Internal party divisions and pressure from rival factions have forced changes in position from both the UK government and opposition.
The ruling Conservative party is riven between Eurosceptic and Europhile factions. The main Labour opposition has seen tension between its largely pro-EU membership and a leadership more inclined to deliver Brexit.
Both the Tories and Labour have suffered defections of some MPs to a new pro-EU centrist party — "Change UK – The Independent Group (TIG)" — for reasons that include their leaders' stances on Brexit.
Tory turmoil boils over
At the heart of the debate over Europe in the United Kingdom is the balance to be struck between two objectives: a desire for independence, sovereignty and autonomy against the need to retain access to European markets, which, the EU has always insisted, means adhering to EU rules.
The defeated UK-EU exit deal represented a compromise. But the blurring of several of Theresa May's so-called "red lines" on the limits of EU power sparked fury within her Conservative Party, for decades split by an internal conflict over Europe. As negotiations with Brussels brought more UK concessions, a string of government resignations followed.
After the 2017 general election, which left the Tories severely weakened in parliament, hostility amid their own ranks to any moves towards a "softer" Brexit restricted May's room for manoeuvre. Eurosceptics including the DUP strongly opposed her Brexit plan and the subsequent agreement, with many calling for the UK to leave the EU with no deal. They argue the accord ties the UK too closely to EU rules, compromising independence perhaps far into the future.
Equally, several pro-EU MPs also opposed a deal which, in their view, would leave the UK worse off than it had been inside the bloc. Some joined calls from opposition parties for a second referendum to see whether the country had changed its mind on Brexit.
Pressure from Tory Europhiles obliged the prime minister to open the door to a Brexit delay. But on the substance of the deal itself, despite talks with other parties she long resisted calls from the Labour opposition for the UK to remain in a customs union with the EU – until her sudden change of tack on April 2.
Read more: What is Theresa May's view on Brexit?
What is the stance of UK opposition parties?
The main opposition Labour party says it respects the result of the June 2016 referendum. Its priorities are to secure a customs union with the EU and access to its markets, as well as ensuring the protection of standards over the environment, and consumer and workers' rights.
The party has backed a new EU referendum under certain conditions, not in all circumstances. Its National Executive Committee agreed on April 30 to support Labour's alternative plan for Brexit, and back a public vote if it can't secure changes to the government's deal or a general election.
The issue has caused internal divisions. Leader Jeremy Corbyn had resisted another referendum, and many MPs in Brexit-supporting constituencies are also hostile. But he has come under intense pressure from the party's largely pro-EU membership, and some prominent frontbench figures wanted any deal agreed by parliament to be put to a confirmatory public vote.
The Scottish National Party (SNP), the pro-EU Liberal Democrats and the newly formed Change UK – The Independent Group (TIG) of breakaway centrist MPs all oppose Brexit, and support a second referendum on the UK's EU membership.
A history of UK-EU tension
Check out our series on the history of the United Kingdom's complicated relations with the European Union: