Lawmakers have submitted alternative proposals - known as amendments - for the next steps on Brexit, which could also be voted upon later. Voting is expected to begin around 1900 GMT. Any amendments which are selected by the speaker will be voted upon one by one.
If any amendments pass, they will either alter the wording of the government plan, or replace it entirely with an alternative. If all the amendments fail, the government proposal will be voted upon last. Below are details of the key votes:
GOVERNMENT MOTION The government statement, which will be the basis of the debate, says two things:
1) That parliament rejects leaving the EU without a deal on March 29 2) notes that leaving without a deal remains the legal default unless a deal is agreed.
May told her party that they would be able to vote according to their conscience on this motion, instead of imposing a party instruction to vote for or against it. MANAGED NO-DEAL BREXIT
This amendment is supported by lawmakers from across the spectrum of views within May's Conservative party, and also has support of the deputy leader of the Northern Irish party that helps keep her minority government in power. It is a plan to try to mitigate the consequences of leaving without a deal by:
1) Seeking to agree with the EU to delay Brexit until 2259 GMT on May 22 this year in order to allow businesses to prepare for a new tariff regime. 2) Seeking a series of 'standstill agreements' with the EU to effectively create a transition period in which little would change. This period would be used to negotiate a permanent future relationship with the EU.
The standstill would not extend beyond the end of Dec. 2021, and Britain would agree to make payments to the EU during this time. 3) Calling on the government to unilaterally guarantee the rights of EU citizens resident in Britain.
The EU has already said the only way Britain can have a transition period is through a negotiated withdrawal agreement, and has rejected the idea of other case-by-case deals to have the same effect. Nevertheless, the idea is popular within May's party as a way to unify the pro-EU and eurosceptic wings of her party. The government has previously engaged with the idea, which is part of a plan known previously as the 'Malthouse Compromise', but it has not become official policy.
Conservative lawmakers will be allowed to vote according to their conscience on this amendment. NO MORE NO-DEAL BREXIT
This amendment has support from lawmakers in several parties, including May's Conservatives, and simplifies the government motion in an attempt to rule out a no-deal exit under any scenario. (Reporting by William James; editing by Michael Holden)