British Prime Minister Theresa May will trigger Britain's withdrawal from the European Union under Article 50 of the EU treaty on March 29, her spokesman said on Monday.
The country should be out in two years. Here is a timeline:
March 25 - The other 27 EU leaders meet in Rome to mark 60 years since the bloc's founding treaty. To avoid spoiling the party, May will wait until following week to file Britain's divorce notice.
March 29 - May will write to European Council President Donald Tusk to trigger the withdrawal process.
March 29-31 - Within 48 hours, Tusk sends to the 27 other member states his draft negotiating guidelines.
April 29 - The other 27 EU leaders meet to agree final guidelines and mandate the EU executive's Michel Barnier to negotiate.
May 5 - Barnier will quickly reply to leaders with his detailed recommendations of how to structure talks. Holidays on May 8-9 may push him to get them to Council within a day.
May - Ministers in the EU's normally low-key General Affairs Council will be called, again excluding Britain, to agree legal "negotiating directives" that will bind Barnier and his team.
After nearly a year of phoney war since the June 23 referendum vote to quit, British negotiators led by Brexit Secretary David Davis will sit down with the EU, possibly still in May. Talks may start with what to discuss first and how to split up topics.
December 2017 - Brussels wants a basic deal on a Withdrawal Treaty by year's end. Key issues: the exit bill for Britain's outstanding commitments; treatment of British and EU expats; dealing with outstanding EU legal cases; new border rules.
2018 - May wants to negotiate a comprehensive free trade deal. Few see two years as enough time to agree one and Brussels wants to hold off starting talks until after a divorce deal. But London and some EU states may push for parallel trade talks.
October 2018 - Barnier's target to finalise the Withdrawal Treaty, to give time for ratification by the European Parliament and a majority in the European Council by March 2019.
Autumn 2018 to Spring 2019 - Just to make things complicated, the Scottish government wants an independence vote once Brexit deal is clear. But May has so far rejected the call for a new Scottish referendum until after Britain leaves the EU.
March 30, 2019 (tentative) - Britain leaves. At any rate, it should do so two years after May writes. It happens to be a non-working day, a Saturday. And avoids April Fool's Day, April 1.
The date could be fine-tuned. Britain could leave earlier if it gets a deal, and the two-year deadline can be extended if all agree. But Brussels wants Britain out before EU elections in May 2019. Despite mutual threats of no deal, few want such chaos.
May and EU leaders say transitional arrangements may well be needed, to give more time to agree a future trade deal and give people and businesses time to adjust to the divorce. Many see another two to five years after Brexit for a final settlement.
If Scotland votes for independence, expect more years to negotiate its split from London and possible re-entry to the EU.