Ministers in Britain have struck a deal on a further year of transition after the country leaves the European Union in order to help prevent a hard border on the island of Ireland.
The UK will propose the customs arrangement – widely known as a "backstop" plan – to ensure people and goods can still move between Northern Ireland and the Republic of Ireland after Brexit occurs in March next year.
The agreement appeared to be a compromise with Prime Minister Theresa May to ensure the UK's Brexit minister David Davis did not resign from the cabinet.
Davis had demanded the backstop plan did not last indefinitely and convinced May to confirm that any transitional period would have to end before the year 2022.
The one-year backstop plan would come after an almost two year transition period following Britain's departure from the EU in 2019.
Thursday's deal may have prevented Davis from resigning, but there was no guarantee Europe would be accepting it.
The EU's chief Brexit negotiator Michel Barnier said he welcomed the UK proposal, and would now examine it to see if it avoided an Irish hard border and respected EU's single market and customs union.
"The UK is clear that the temporary customs arrangement, should it be needed, should be time limited," the document, which was published online and sent to Brussels, said.
"The UK expects the future arrangement to be in place by the end of December 2021 at the latest. There are a range of options for how a time limit could be delivered, which the UK will propose and discuss with the EU."
Thursday's row was another sign of May's difficulties keeping her ministers and the governing Conservative Party in agreement as she drives exit negotiations with the European Union.