Made in Britain: What does it mean for trade after Brexit?
There are significant costs, administrative and legal, for businesses that have to prove the origin of goods. In some cases, that could even mean that it's cheaper just to pay a low tariff than to go through the bureaucracy involved in getting an exemption. "There are steps that can be taken to mitigate the costs," says Sam Lowe of the Centre for European Reform. "But outside the customs union you cannot eliminate those extra costs entirely."