Bill must be debated by both houses and receive royal assent to meet Theresa May’s self-imposed 31 March deadline

24 January: The supreme court delivered a ruling that the government must seek parliamentary approval to invoke article 50.



26 January: Theresa May published her one-page, two-clause Brexit legislation aimed at giving her the authority to take the UK out of the EU.

31 January and 1 February: The Brexit bill’s passage through parliament begins with an initial two-day debate in the House of Commons, known as a second reading. At the end of the second day of debate, there will be a vote on whether to send the legislation to its next parliamentary stage.

2 February: Theresa May could publish her white paper – setting out the government’s formal policy position on Brexit – as early as Thursday.

6 and 7 February: The bill will begin its committee stage in the Commons, which gives MPs an opportunity for further scrutiny and attempts at revision. They can try to change the bill by pushing through a series of amendments, although it is unlikely any will pass without the support of significant numbers of rebel Tory MPs.

8 February: At the end of the committee stage, MPs will get another chance to debate the bill, followed by a final vote. The bill is almost certain to pass and be sent to the Lords.

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20 February: The House ofLords is likely to begin debating the bill after parliament returns from recess. This may continue for some days. If peers vote to amend the bill, it will return to the Commons and continue to pass back and forth in a process known as “ping-pong” until the text is agreed. If there are no amendments, the bill is sent to the Queen to receive royal assent and become law.

7 March: The government hopes the Brexit bill will have passed through the Lords by this date. Once the bill has received royal assent, May will be able to trigger article 50 at any point thereafter.

9 and 10 March: May could use the occasion of an EU summit in Brussels to formally trigger article 50 and start the two-year countdown to the UK leaving the EU.

31 March: This is the self-imposed deadline set by May for invoking article 50 by notifying the European council of Britain’s intention to leave the EU.