The UK’s public spending watchdog said government expenditures on implementing new rules for post-Brexit imports would total some $6 billion. The report criticized “uncertainty” surrounding government plans.

Britain will spend at least 4.7 billion pounds ($6 billion, €5.5 billion) on implementing a new approach to import goods after exiting the EU customs market in 2020, the UK government’s public spending watchdog said on Monday.

The UK voted to leave the European Union in 2016 but remained in the bloc’s single market and customs union until 2021.

In 2021, the UK withdrew from the EU customs union and a new EU-UK Trade Cooperation Agreement (TCA) went into effect.

The European Parliament said in a report that the trading of goods between the parties had become “burdensome” since Brexit and trade volumes had shrunk.