Why hasn't Brexit happened yet?

Brexit is the removal of the United Kingdom from the European Union. Following the June 2016 referendum, in which 51.9% voted in favour of leaving, the UK government officially announced the withdrawal in March 2017, launching a process currently to be completed with the UK withdrawal no later than 31 January 2020.

Initially, Brexit was to take place on 29 March 2019. Two years later, Prime Minister Theresa May proposed Article 50, a formal exit process, and opened negotiations.

Under Ms May's leadership, the deadline was twice delayed after MEPs rejected her Brexit deal - eventually postponing it to 31 October 2019.

Following Ms May's replacement as Prime Minister Johnson, she was asked to seek a third extension after MPs failed to issue a revised Brexit Transaction Law.

The new deadline is set for 31 January 2020, three and a half years after the referendum.

After winning the Conservative leadership contest, G. Johnson took over as Prime Minister in July 2019 and renegotiated the Mayan deal.

Johnson succeeded in replacing the support scheme with new customs regulations. Unlike the previous deal, the revised deal will allow Britain to sign and implement its trade agreements with countries around the world.

However, the revised transaction effectively creates a customs and administrative border between Northern Ireland and the United Kingdom. This means that some goods coming to Northern Ireland from the UK will be screened and paid EU import duties (known as tariffs).

They will be refunded if the goods remain in Northern Ireland (ie not moved to the Republic of Ireland).

Assuming the European Parliament also gives the green light, the UK will officially leave the EU on 31 January with a withdrawal deal.

However, this would only mark the next step in the Brexit process. After its departure, the United Kingdom will enter into a transitional period until 31 December 2020.

Britain's trade relations with the EU will remain unchanged during this period while both sides negotiate a free trade deal. At the same time, many other aspects of the UK's future relationship with the EU will need to be agreed, including law enforcement, data sharing and security.

If the trade deal is ready in time, the UK's new relationship with the EU can begin immediately after the transition. If not, the United Kingdom has the prospect of trading without a valid contract. This would mean checks and tariffs on British goods going to the EU.