When did brexit start and end

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.

The government has known about this for years, and has made plans to divert trade to other ports around the country and has built lorry parks in Kent, to avoid gridlock on the roads.

It's difficult to predict what the scale of any disruption might be, but government minister Michael Gove has said that UK businesses should prepare for some "bumpy moments".