Experts estimate that raising the income barrier for qualified workers to get a British visa may cost the country £25 billion over a ten-year period.

The massive projected cost of raising the threshold from £26,200 to £38,700 starting in April of this year was emphasised by the Oxford Migration Observatory.

According to the analysis's baseline budgetary conclusions, raising the threshold would save £7 billion over ten years, but it would also cost £32.5 billion, leaving a £25.5 billion net deficit.

Dr Madeleine Sumption, director of the observatory, said: “The impacts of higher salary thresholds for skilled workers will depend a fair amount on how employers respond.

“If employers respond by hiring fewer workers, particularly people at the higher pay levels who tend to pay the most tax, the costs to public finances are expected to be larger.

“If on the other hand they still recruit migrant workers and simply pay them more, this has costs to employers but could actually benefit public finances at least in the short run. As a result, the impact of this policy change is particularly difficult to judge.”

She added: “It’s still too early to say how employers are responding to the change.

“Over the few months since the salary thresholds were introduced we have seen a decline in the number of workers sponsored, but perhaps not as dramatic as one might have expected given how much salary requirements increased.”

Restricting visas for most international students’ dependants also had a negative impact on the UK public finances, but far smaller.

The fiscal benefit was put at slightly over £22 billion, but the cost at £22.6 billion, a net blow of £0.55 billion.

However, restricting visas for care workers’ dependants had a net benefit of £29.8 billion, with the costs being £59.87 billion, and benefits just over £30 billion.

In the paper on the fiscal impact of immigration in the UK, the Oxford experts stressed: “While the impact assessments have typically found that policies leading to higher levels of work or study migration have positive net fiscal impacts in the short run, this is not always the case.

“For example, the decision to restrict visas for care workers’ dependants in 2024 was expected to generate an average net fiscal benefit of £3 billion per year over 10 years (in 2024/25 prices).

“This was on the basis that the children of migrant care workers would be prevented from coming to the UK, leading to lower levels of public spending on education and healthcare.”

The new Government, after it came to power in July, backed the rise in the salary threshold for skilled workers despite business chiefs warning that it was making it harder for them to recruit key staff.

New Home Secretary Yvette Cooper also asked the Government’s migration advisers to review key sectors “where labour market failures mean there is over-reliance on international recruitment”.

She asked the Migration Advisory Committee to specifically look at the IT and engineering sectors as part of the inquiry, as they had “over a decade or more, been included on shortage occupation lists and relied on significant levels of international recruitment”.

A Home Office spokesperson said: “This government is clear that net migration must come down and that immigration should not be used as an alternative to tackling skills shortages here in the UK.

“While these impact assessments show levels of legal migration will reduce, we are going further by setting out a new approach to link the UK’s immigration, labour market and skills systems to train up our own homegrown workforce, end the over reliance on international recruitment and boost economic growth.”