"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 to be sure that 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."
"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.
"This is the biggest imposition of red tape that businesses have had to deal with in 50 years," according to William Bain from the British Retail Consortium.
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. So if businesses are not prepared, or do not fill in the new paperwork correctly, it could cause delays and backlogs at ports like Dover."
"...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 tariffs (charges on imports) being imposed on some goods in the future.
Expect the threat of disputes to be a new constant in UK-EU relations."
