Published on Friday, the report by the Royal College of Nursing (RCN) examined almost 400 cases involving health and care staff who sought support after reporting alleged exploitation and extortion between 2023 and 2025.
While this number is far higher than it should be, the RCN warned these cases only represent a small proportion of the problem - some workers could be reluctant to raise concerns because of fears about their immigration status.
The RCN said employers had used sponsorship rules to demand large repayments, cut pay, change contracts and leave unsafe working practices unchallenged.
More than half of the cases involved employers using repayment clauses against staff who wanted to leave before the end of their contracts. The union said most demands exceeded the £3,000 maximum recommended by NHS Employers, with one case involving a request of £25,000.
Hourly pay was flagged as an issue in one in five cases, with many workers reporting they were paid less than the rate agreed in their contracts.
Poor workplace conditions were also highlighted. More than half of cases involved concerns about employment practices - some included allegations of bullying, harassment and racism.
Professor Nicola Ranger, chief executive and general secretary of the RCN, said: 'This report exposes the scale of grotesque exploitation taking place in the sector.
'A National Care Service meeting the needs of an ageing population with complex conditions will need to be registered nurse-led. We're the ones with the skill and expertise to make it work, but that cannot happen while so many of our migrant colleagues are being exploited.'
The report comes a week after prime minister Andy Burnham announced plans for a National Care Service and praised the contribution of migrant workers who cared for his father.
'Migrant workers are routinely intimidated and left fearful of speaking out,' Nicola added. 'The prime minister has spoken movingly about the contribution of migrant nursing staff, now they need his full backing.'
On the subject of support, the RCN is calling for changes to the immigration system, including allowing migrant nursing staff to move between employers without risking their right to remain in the UK.
The union also wants the planned Fair Work Agency to monitor employment practices and for the time workers have to find a new employer after losing sponsorship to be extended from 60 to 180 days.
Commenting on the report, Dr Jane Townson OBE, chief executive of the Homecare Association, said exploitation of social care nurses is 'indefensible in any form.'
'The practices this report describes, including unlawful fees, excessive repayment clauses, coercion and harassment, have no place in homecare or anywhere else,' Townson added.
'Every provider is accountable for the way it treats its workers, and system pressures are never an excuse for mistreating people.
'Enforcement alone, however, will not build a fair system. We need improvements in commissioning and market shaping, a fair price for care through a national contract, fair pay and secure income for workers, and fair regulation that roots our exploitation.'
