If Scotland were to become an independent country, there would be a new international border with the rest of the UK. The additional costs that are inevitably created by borders would affect trade, making it harder for Scottish firms to do business with the rest of the UK.
Borders between countries create additional costs for businesses, which lead to lower levels of trade. As the rest of the UK accounts for over 60% of Scotland’s exports, the Scottish economy would be vulnerable to an increase in border costs should it become independent. But there is considerable uncertainty over how substantial the economic effects of introducing a border with the rest of the UK would be.
Focusing only on changes in international trade, independence would be expected to have a negative effect on the Scottish economy because of higher border costs. And rejoining the European Union (EU) would not necessarily offset the border costs of independence. This is because Scotland currently trades around four times more with the rest of the UK than it does with the EU.