Explained: Brexit's Divorce from European Union is now formal

After months of negotiations, the UK and European Union finally agreed a deal that will define their future relationship, which came into effect at 23.00GMT on 31 December.

The deal contains new rules for how the UK and EU will live, work and trade together. While the UK was in the EU, companies could buy and sell goods across EU borders without paying taxes and there were no limits on the amount
of things which could be traded.

Under the terms of the deal, that won't change on 1 January, but in order to ensure neither side has an unfair advantage, both sides had to agree to some shared rules and standards on workers' rights, as well as many social and environmental regulations.

Freedom to work and live between the UK and the EU also comes to an end, and in 2021, UK nationals will need a visa if they want to stay in the EU more than 90 days in a 180-day period.

Northern Ireland will continue to follow many of the EU's rules in order to avoid a hardening of its border with the Republic of Ireland. This will mean however that new checks will be introduced on goods
entering Northern Ireland from the rest of the UK.

Now that it's no longer in the EU, the UK is free to set its own trade policy and can negotiate deals with other countries. Talks are being held with the US, Australia and New Zealand – countries that currently
don't have free trade deals with the EU.

<strong>Disruption at the borders?</strong>

There may not be new taxes to pay at the border, but there will be new paperwork, and the potential for it to cause delays is a serious concern.

Businesses fear there will be red tape.

The UK says it will delay making most checks for six months, to allow people to get used to the new system, but the EU will be checking paperwork and carrying out checks from day one.

<strong>Some loose ends?</strong>

Decisions are still to be made on data sharing and on financial services, and the agreement on fishing only lasts five years. Also while the UK and EU have agreed to some identical rules now, they don't have to be identical in the future, and if one side takes exception to the changes, they can trigger a dispute, which could ultimately lead to customs duties being imposed on some goods in the future..