Brexit deal: What happens next and what will change on January 1?

The clock, as Michel Barnier said, is no longer ticking.

Some four-and-a-half years after a slim majority of Britons voted to take the United Kingdom out of the European Union’s orbit, the UK and the EU finally signed a historic trade deal

The 660 billion pounds ($900bn)-a-year pact will determine the terms of the pair’s relationship from 2021 onwards and was reached after months of missed deadlines, acrimonious posturing and fraught negotiations marred by divisions over fishing rights, competition rules and governance issues.

The deal came exactly one week before the UK is due to exit the EU’s single market and customs union on December 31, when the Brexit transition period ends.Announcing the breakthrough agreement, Barnier, the EU’s chief Brexit negotiator, on Thursday said it was a “day of relief” tinged with “some sadness as we compare what came before with what lies ahead”.

The UK and the EU parliaments must move quickly to ratify the deal, which is yet to be published but thought to be about 1,500 pages long.

It is expected that both legislative bodies will sign off on the agreement. However, due to the short window of time left in the transition period, it will not be fully ratified until next year.

British Prime Minister Boris Johnson plans to put the agreement to the UK Parliament for a vote on December 30.