Theresa May will trigger the two year process of leaving the European Union on March 29th, No 10 have announced.
Tim Barrow, the UK's ambassador to the EU, formally notified the office of EU Council president Donald Tusk this morning.
Notification of Britain’s plans to leave the EU took place this morning with a letter from Sir Tim to the office of Mr Tusk.
On Wednesday next week Mrs May will formally notify Mr Tusk by writing him a letter and then giving a statement to MPs later in Parliament.
The PM’s official spokesman said: “There will be a letter. We have always been clear we would trigger by the end of March and we have met that timetable.”
The spokesman declined to comment at this stage on the contents of the letter nor on whether there would be any further documents published next week.
Number 10 said it expected a response within 48 hours from Mr Tusk.
Downing Street also ruled out an early election, saying: “There is not going to be one."
It comes after speculation that Mrs May was considering calling an election before 2020, the date when the next one is due under the Fixed-term Parliaments Act.
Mrs May revealed ahead of her first speech as Prime Minister at the Tory Party Conference that she would trigger Article 50 no later than the end of March 2017.
But she was accused of “losing momentum” and “making errors” by delaying the formal start of Brexit talks in the wake of Nicola Sturgeon’s shock demand for a Scottish independence referendum.
The Prime Minister was expected formally to start negotiations with other European Union member states last week, after Parliament had passed a law allowing talks to begin.
Responding to the announcement, the Secretary of State for Exiting the European Union David Davis said: "Last June, the people of the UK made the historic decision to leave the EU. Next Wednesday, the Government will deliver on that decision and formally start the process by triggering Article 50.
"We are on the threshold of the most important negotiation for this country for a generation.
"The Government is clear in its aims: a deal that works for every nation and region of the UK and indeed for all of Europe – a new, positive partnership between the UK and our friends and allies in the European Union."