The UK could receive an extension to the withdrawal period by 3 months or up to 2021 under Article 50 of the Treaty on European Union. The House of the Commons will have a “meaningful vote” on Theresa May’s revised Brexit deal no later than March 12th, a yes-or-no vote to approve the PM’s plan.
If it fails, then the UK will allow a vote on whether to have a no-deal Brexit and leave the EU. If no-deal Brexit is rejected then the MPs will vote to extend the Article 50 period, potentially prolonging the UK’s commitment to the EU past March 29th. The vote of extension will occur no later than Thursday, March 14th.