13/03/2017 07:29 GMT | Updated 14/03/2017 09:30 GMT

When Will Article 50 Be Triggered? Everything You Need To Know About The Brexit Bill

It's crunch time.

A landmark law giving Theresa May the power to start Britain’s withdrawal from the European Union faces its final Parliamentary hurdle later.

The Brexit Bill will allow the Prime Minister to commence negotiations with the EU under Article 50, a process that can take a maximum of two years from the time it is triggered.

Reuters Photographer / Reuters
The Brexit Bill returns to the House of Commons on Monday afternoon

What is happening today?

The Bill returns to the Commons on Monday afternoon where Lords’ amendments will be voted on. It will then be sent back to the Lords in the evening - the final stage before it passes into law. 

What might slow things down?

Up to 10 Tory MPs are reportedly considering opposing the Government or abstaining in the vote but a rebellion would need to reach higher numbers to derail the process, the Press Association reported.

Labour sources warned there was a 20% chance of peers sending the Bill back to the Commons again if their amendments are dismissed out of hand, in another round of so-called Parliamentary ping-pong.

But other reports say the Lords will pass the Bill.

When will Article 50 be triggered?

If the Brexit Bill passes into law without a challenge, Theresa May can finally trigger the formal process for leaving the EU, as early as Tuesday.

Last updated: Tuesday 14 March. Find the latest Brexit news here.

Carl Court via Getty Images
Theresa May could trigger Brexit as early as Tuesday

It comes as MPs are likely to overturn changes to the Brexit Bill made by peers when it returns to the Commons on Monday afternoon.

Backing by the Lords when the legislation is sent to the upper chamber in the evening would allow the Prime Minister to fire the starting gun on exit talks as early as Tuesday.

Brexit Secretary David Davis called on Parliament to give May a clear run at the two-year negotiation process that will begin when Article 50 is triggered.

Reuters Photographer / Reuters
Brexit Secretary David Davis called on Parliament to give May a clear run at the two-year negotiation process

“Please don’t tie the Prime Minister’s hands in the process of doing that for things which we expect to attain anyway,” he told BBC One’s The Andrew Marr Show.

“What we can’t have is either House of Parliament reversing the decision of the British people.”

The House of Lords changed the European Union (Notification of Withdrawal) Bill to introduce a ‘’meaningful’’ parliamentary vote on the final deal with Brussels and guarantees on protections for EU nationals living in Britain.

May will go before MPs on Tuesday to update them on talks she had with other EU leaders at a European Council meeting last week.

Speculation is mounting she will use the opportunity to formally announce she is starting the exit process, although there is still plenty of time before the self-imposed deadline of the end of March.

International Trade Secretary Liam Fox refused to be drawn on the timing, insisting only it would be within the next three weeks.

The Cabinet minister admitted crashing out of the EU without a Brexit deal would be “bad” for Britain and said it was “not in anybody’s interest” for the talks to end in failure.

But Foreign Secretary Boris Johnson insisted Britain “would be perfectly okay” if no agreement was reached and it would not be “as apocalyptic as some people like to pretend”.

Former minister Anna Soubry, meanwhile, claimed talks could collapse within six months and leave Britain falling off a cliff-edge.

Quitting without a deal and moving to World Trade Organisation (WTO) rules would put UK trade with the EU on less generous terms than any other country in the G20, according to House of Commons Library research.

All of the leading nations have some form of preferential agreement with Brussels, ranging from full free trade agreements to equivalence deals.

Labour’s Pat McFadden, a supporter of the Open Britain campaign to keep strong ties with the EU who commissioned the research, warned threatening to walk away without a deal was “dangerous”.

“The Government is flirting, as a negotiating tactic, with an option that poses huge dangers to UK industry, services and agriculture,” he said.

“This is why it is vital for Parliament to have a meaningful say in the negotiations to come, and to have a say on both a Free Trade Agreement and what should happen in the event of no deal being agreed.”