More than 3 million citizens of other EU countries live in Britain, and many sectors of the economy rely on foreign workers.
Home Secretary Amber Rudd said today that the government needs "the most accurate picture possible of the extent to which the UK economy uses EU labor." She has asked an independent group, the Migration Advisory Committee, to conduct the study.
The government says it will end free movement a key principle of the EU and impose immigration controls after Brexit. But businesses say it is unclear exactly what will happen when Britain ceases to be an EU member in March 2019.
Rudd said there would be no "cliff-edge" for the economy, suggesting a transition period. But Immigration Minister Brandon Lewis said Thursday that free movement will end in the spring of 2019.
Critics say the government has been tardy in calling the inquiry, which is not due to report until September 2018 six months before the Brexit deadline.