Parliament has officially agreed to delay Brexit until April 12 at the earliest, after approving legislation to match the agreement Theresa May signed with the EU.
Last week the European Council agreed that the original Article 50 process would be extended beyond March 29 - this Friday.
MPs voted earlier this month overwhelmingly to request a delay to avoid a no-deal exit.
To bring domestic UK law into line with the change, MPs had to update the EU Withdrawal Act.
The Commons voted in favour of this by 441 votes to 105 - a majority of 336.
May told MPs on Wednesday the change was needed to avoid legal confusion.
But to the fury of hardline Brexiteer Conservatives, the PM said they could not stop a delay even if they voted it down.
“It’s a matter of international law that the date of the UK’s exit has been changed,” she said.
Former Tory cabinet minister Lord Forsyth hit out at what he called “a conspiracy by Remainers” to delay Brexit.
And another former Conservative minister, Lord Robathan, said the prime minister had said more than 100 times in parliament that the UK would leave the EU on March 29.
“One has to ask... whether anyone will trust anything she says again,” he said.
Tory MP Steve Double said delaying Brexit was a “break of trust” with the public.
Labour’s shadow Brexit minister Matthew Pennycook said May only had herself to blame for the delay.
“No-one, including those who have no problem with an extension, expected that this government would fail so miserably that an extension of any kind would be required,” he said.
The UK is now on course to leave the EU on May 22 if MPs approve May’s Brexit deal this week.
If the Commons rejects it for a third time, then the UK will exit the bloc on April 12 without a deal unless alternative can be found.
May’s chances of winning a third meaningful vote on her deal appear to have been boosted after she made a dramatic pledge to resign as PM before the next stage of Brexit negotiations.
She did not name a date for her departure, but her announcement sets the stage for a Conservative leadership election within the coming weeks or months.
Her offer to resign after her Withdrawal Agreement is passed came in response to calls from a number of her backbenchers for her to promise to go in return for their help in pushing the deal through parliament.
The last ditch plea led to Boris Johnson, a possible leadership contender, deciding to u-turn and announce he would back the deal.
May spoke to the influential Tory 1922 Committee shortly before MPs were due to take part in “indicative votes” on a range of Brexit options in Commons.
She said she “will not stand in the way” of the party having new leadership, telling the 1922 Committee: “I am prepared to leave this job earlier than I intended in order to do what is right for our country and our party.”
However despite May’s chances of passing her deal remain slim, given the continued opposition of hardline Brexiteer Tories and the DUP.