May to trigger Brexit on March 29
Britain's ambassador to the EU, Sir Tim Barrow, informed the office of European Council president Donald Tusk on Monday morning of the Prime Minister's plans.
It is not quite accurate to say nothing much is going to happen after article 50 is triggered next week, but the huge excitement built up around "the date" is likely to prove misplaced.
The pound on Monday fell against the USA dollar after confirmation of the date Brexit negotiations will begin.
Mr Margaritis Schinas, spokesman for EC chief Jean-Claude Juncker, said: "Everything is ready on this side". May spokesman went on: "After we trigger the 27 will agree their guidelines for negotiations and the Commission will deliver their negotiating mandate".
A majority of Britons voted to leave the European Union at a referendum in June.
Jean Claude Juncker, as European Commission president, will oversee the process, while Barnier and his taskforce of negotiators deal with the United Kingdom government for the next two years.
London has repeatedly said it wants to maintain good relations with its European allies, but major battles await, in particular over budget contributions, immigration and future trade ties.
"The Government is clear in its aims: a deal that works for every nation and region of the United Kingdom and indeed for all of Europe". We want negotiations to start promptly.
"I have set out my objectives", she said.
Tusk said he would issue draft guidelines for the negotiations within 48 hours, and officials said European Union leaders are then likely to meet at a special summit in early May to approve them.
"It's fascinating that the pound sunk quite so quickly as we knew the end of March was the preferred date".
In Northern Ireland, which also voted to stay in the European Union, the largest Irish nationalist party Sinn Fein has said it wants a referendum on splitting from the United Kingdom and uniting with the Republic of Ireland "as soon as possible". Britain will not actually leave the European Union until early 2019, ideally having tied up a mutually acceptable exit deal.
British prime minister Theresa May is due to make a statement to the House of Commons the same day.
Parliament could be tasked with scrutinising up to 15 new bills to deliver Brexit, leaving little time for other unrelated legislation, the Institute for Government has warned.
The Prime Minister is attempting to reach out in order to address criticisms that she is not paying proper attention to different administrations.
EU leaders have said they want to conclude the talks within 18 months to allow the terms of the UK's exit to be ratified by the UK Parliament and the European Parliament, as well as approved by the necessary majority of EU states.
Negotiations will begin to outline a UK Brexit deal, which could include trade deals - although this might be handled separately.