BRUSSELS (Reuters) - Prime Minister Theresa May will write to European Council President Donald Tusk by the end of this month to trigger Britain's withdrawal from the European Union under Article 50 of the EU treaty.
The country should be out in two years. Here is a possible timeline:
March 25 - The other 27 EU leaders meet in Rome to mark 60 years of founding treaty. May wants to avoid spoiling the party.
March 27-30 - Last four days of parliament, where May says she will announce her move. A spokesman has stressed she planned to send the trigger letter at "the end" of the month.
March 29-31 - European Council President Donald Tusk will, within 48 hours of receiving May's letter, distribute to the 27 member states his draft negotiating guidelines.
May 4 - Tusk needs about four weeks to prepare a summit he will chair of the 27 to agree final guidelines and mandate the EU executive's Michel Barnier to negotiate. With Easter on April 16, the first round of French presidential voting on April 23, public holidays on May 1 and the French runoff on May 7, May 4 is a possible date.
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 nine months of phoney war since the June 23 referendum vote to quit, British negotiators led by Brexit Secretary David Davis will sit down with 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 Withdrawal Treaty by year's end, e.g.: 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 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. An idea of customs plans may be needed to resolve eg. Irish border problem.
October 2018 - Barnier's target for Withdrawal Treaty, to give time for ratification by the European Parliament and a majority in the European Council by March 2019.
November 2018 - Just to make things complicated, Scottish government wants independence vote once Brexit deal clear.
March 30, 2019? - Britain will leave the EU. At any rate, it should leave 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 EU.
Editing by Catherine Evans