EU leaders have agreed on a plan to delay the Article 50 process, postponing Brexit beyond 29 March, BBC reports.
The UK will be offered a delay until 22 May, if MPs approve the withdrawal deal negotiated with the EU next week.
If they do not, the EU will back a shorter delay until 12 April, allowing the UK time to get the deal through or to "indicate a way forward".
Mrs May said there was now a "clear choice" facing UK MPs, who could vote for a third time on her deal next week.