The Home Office failed to gather "basic information" about migrants who came to Britain on visas and left foreign workers "vulnerable to exploitation", the chairman of a cross-party committee of MPs has warned.
An inquiry report, published on Friday, revealed data on whether people had left the UK after their visas expire or how many might have stayed to work illegally was not collected by the government.
The Public Accounts Committee (PAC), which examines the value for money of government projects, said the Home Office had not analysed exit checks since the skilled worker visa route was introduced under the Conservatives.
This is despite some 1.18 million people applying to come to Britain via this route between December 2020 and the end of 2024 as ministers attempted to attract skilled workers in the wake of Brexit.
Around 630,000 of those migrants were family members or dependants of the main visa applicant.
The PAC said there is a lack of knowledge around what people do when their visas expire.
MPs warned that the expansion of the route in 2022 to attract staff for the struggling social care sector led to the exploitation of some migrant workers who found themselves in "debt" to abusive employers.
Its report said there was "widespread evidence of workers suffering debt bondage, working excessive hours and exploitative conditions".
It noted that the fact a person's right to remain in the country is dependent on their employer under the sponsorship model means migrant workers are "vulnerable to exploitation".
But it adds that there is "no reliable data on the extent of abuses".
Committee chairman Sir Geoffrey Clifton-Brown said while the then-Tory government had "moved swiftly to open up the visa system to help the social care system cope during the pandemic", the speed and volume of applications "came at a painfully high cost to the safety of workers... and the integrity of the system from people not following the rules".
"There has long been mounting evidence of serious issues with the system, laid bare once again in our inquiry," he said.
"And yet basic information, such as how many people on skilled worker visas have been modern slavery victims, and whether people leave the UK after their visas expire, seems to still not have been gathered by government.
“Further changes are now underway in this system, with an end to the overseas recruitment of care workers. Without effective cross-government working, there is a risk that these changes will exacerbate challenges for the care sector.
"Government now needs to develop a deeper understanding of the role that immigration plays in sector workforce strategies, as well as how domestic workforce plans will help address skills shortages.
"Government no longer has the excuse of the global crisis caused by the pandemic if it operates this system on the fly, and without due care.”
Figures published earlier this year suggested thousands of care workers have come to the UK in recent years under sponsors whose licences were later revoked, in estimates suggesting the scale of exploitation in the system.
The Home Office said more than 470 sponsor licences in the care sector had been revoked between July 2022 and December 2024 in a crackdown on abuse and exploitation.
More than 39,000 workers were associated with those sponsors since October 2020, the department said.
In its report, the PAC said: "The cross-government response to tackling the exploitation of migrant workers has been insufficient and, within this, the Home Office's response has been slow and ineffective."
It also noted a lack of information around what happens to people when their visas expire, stating that the Home Office had said the only way it can tell if people are still in the country is to match its own data with airline passenger information.
"The Home Office has not analysed exit checks since the route was introduced and does not know what proportion of people return to their home country after their visa has expired, and how many may be working illegally in the United Kingdom," the report states.
Home Secretary Yvette Cooper said the issues were “part of the broken immigration asylum system that we inherited”.
She told LBC on Friday: “What we're doing is, first of all, net migration is coming down now... bringing in new controls on who arrives in the first place, and bringing in new exit checks and stronger systems to link up E visas with the entry and exit checks, and to link those as well with the biometric systems.
“When we go on illegal working enforcement raids, which have got also up 50%, they can do biometric checks, fingerprint checks, immediately, and we can get that data and monitor who's in the country and who isn't.”
