The UK government cannot deliver on the promise to end freedom of movement from the EU on Brexit day because it has no system to work out who is legally in the country, according to the Oxford-based Migration Observatory.

The Home Office said on August 19 that the UK will end freedom of movement on November 1st, immediately, in the event of a no-deal Brexit.

However, the government’s only way to distinguish between “settled” and “pre-settled” EU citizens with the right to reside in the UK and any new arrival is the official settlement scheme. The deadline for EU citizens to enrol in the scheme is December 2020. Of the 3,3 million estimated EU citizens residing in the UK, only one million have enrolled.

In a letter from the Home Office to EU citizens working across the public sector dated August 21, British authorities confirm that EU citizens and their family members in the UK “still have until 31 December 2020 to apply to the EU Settlement scheme, even in the event of a no-deal exit.” Moreover, the letter offers assurances that they are able to leave and reenter the UK “as they are now,” without demands for additional documentation.

Nevertheless, political tension is already having an effect on migration.

EU net migration to the UK has reached its lowest level since 2013 according to the latest data released by the Office for National Statistics. The ONS estimates that 200,000 EU citizens arrived in the year up to March 2019, of which 92,000 with the intention to work. That is less than half their 2016 peak.