The House of Commons is likely to sit into the night after the committee stage for the EU (Withdrawal) Bill, also known as the Great Repeal Bill, begins later.
Theresa May faces the risk of defeat over the key piece of Brexit legislation that will enshrine EU laws in British law on the day Britain leaves the EU.
Almost 500 amendments have been tabled by MPs that support and oppose Brexit but the Commons is only likely to vote on a handful of proposed changes.
The Prime Minister has announced plans to make an amendment to the bill so that Britain must leave the EU at 11pm UK time on March 29 2019.
Although MPs are expected to vote the bill through, the government could be defeated in ammendment votes if about 20 Tory MPs decide to rebel.
In order to avoid defeat, Mrs May and Brexit Secretary David Davis could be forced to make a number of major concessions.
Mr Davis has already made one climbdown by saying that MPs will have a take-it or leave-it vote on the final Brexit deal.
He announced the concession in response to former attorney general Dominic Grieve’s amendment which calls for a meaningful vote.
Mr Grieve said that this reassurance did not go far enough and confirmed that his amendment would remain in place for the time being.
One key challenge will be over the so-called Henry VIII powers that would allow the Government to amend laws EU laws brought on to the British statute book.
Critics warn that the current draft bill would give ministers too much power to make changes without full parliamentary scrutiny.
The second day of the debate will take place tomorrow. But the remaining six days of the debate have not yet been scheduled.
It is thought that there will be two days of debate every week through to mid-December.
Here is a breakdown of the plan for the first and second day of the debate, according to the House of Commons.
Day 1 (Tuesday) could go late into the night
- Amendments on Clause 1 which repeals the 1972 European Communities Act on the day that the UK leave the EU.
This session is likely to deal with the amendments related to the date and time of Britain’s EU exit.
- Amendments on Clause 6 which deals with the jurisprudence of the European Court of Justice (ECJ).
This amendment says the UK courts are not required to follow ECJ judgments after exit day.
Day 2 (Wednesday) could continue into evening
- Debate on Clause 2 which preserves all “EU-derived legislation” which is in force immediately before exit day.
- Debate on Clause 3 which converts “direct EU legislation”, such as directives and regulation, into domestic law.
- Debate on Clause 4 which deals with other rights and provisions of the EU treaties.