Theresa May is next month poised to announce the end of free movement for new EU migrants on the same day that she formally triggers Brexit negotiations.
The Prime Minister is expected to say that EU citizens who travel to Britain after she triggers Article 50 will no longer have the automatic right to stay in the UK permanently.
They will instead be subject to migration curbs after Britain leaves the European Union, which could include a new visa regime and restricted access to benefits.
Mrs May is expected to say that EU migrants who arrived in the UK before the “cut-off date” will have their rights protected as long British citizens living elsewhere in Europe are granted the same assurance.
Iain Duncan Smith, a leading Eurosceptic conservative MP, said that that announcement will show that Mrs May is taking control of Britain’s borders while giving clarity to the 3.6million EU migrants already living in the UK.
He said: “Theresa understands that if you want to take control you have to command the high ground. She will be giving clarity by setting a clear deadline while the European Union looks increasingly muddled and mean-spirited”.
The announcement means that the “cut-off date” for EU migrants is likely to be around March 15, once the Government’s Article 50 bill has gone through Parliament.
The Prime Minister is expected to appeal to other European Union nations to reach a quick deal on the issue so it can be removed from Brexit negotiations as soon as possible.
It is likely to put her in conflict with the European Union, which has been pushing for Mrs May to delay the cut-off date until 2019. However ministers have raised concerns that waiting until the end of negotiations will lead to a huge surge in the number of EU migrants coming to the UK before Brexit.
“We have had some suggestion that that the European Commission might attempt to force us to protect everyone who arrives up to the moment of departure,” a Government source said. “We could end up with half of Romania and Bulgaria coming here if we wait that long.”
The Government has also considered suggestions that the cut-off date should be set for the referendum date in June last year. However Government lawyers have advised that such an approach would be illegal.
Amber Rudd, the Home Secretary, said that after Britain leaves the European Union “we will be ending free movement as we know it”.