It could cost an estimated £63,000 more to send a migrant to a “safe country” such as Rwanda than to keep them in the UK, the government has said.
An economic impact assessment of the Illegal Migration Bill, which is going through Parliament, found a gross cost of £169,000 to relocate an individual.
But the estimated £106,000 spent on housing support if they remained in the UK would be avoided.
The government said the policy would also have a deterrent impact.
However, the Home Office assessment said it was “uncertain” what level of deterrence impact it would have because the bill was “novel and untested”.
It said no cost would be incurred if an individual was deterred from entering the UK illegally.
It also said the potential savings were “highly uncertain” but gave an estimated figure of between £106,000 and £165,000 per individual. The higher figure takes into the account the possibility of housing costs continuing to increase.
Other additional savings beyond accommodation costs include those associated with resettling a migrant in the UK such as benefits, social housing and healthcare.
The report estimates the policy would need to deter 37% of people from entering the UK illegally for there to be no cost to the taxpayer.
The bill aims to stop people crossing the Channel in small boats by preventing anyone arriving in the UK illegally from claiming asylum.
Instead, they would be detained and removed, either to Rwanda or another “safe country”.
The total cost of relocating an individual to Rwanda or another third country includes a payment to that country of around £105,000 per person, as well as £22,000 for flights and escorting the individual.
The figure assumes a flight can seat 50 individuals being relocated but flights may depart with fewer people on board.
Other costs include detaining individuals while they are processed.
The costs are theoretical estimates rather than the actual cost of the Rwanda agreement, which is commercially sensitive.
Labour said the impact assessment was “a complete joke” and the government was “totally clueless” about how much the bill would cost.
“The few figures the Home Office has produced show how chaotic and unworkable their plans are,” shadow home secretary Yvette Cooper said.
She added that “the true cost” may be higher as the government had not costed the possibility of people being held in “indefinite detention”.
Enver Soloman, chief executive of the Refugee Council, said the bill “would cause hardship, cost billions of pounds, and do nothing to alleviate the current crisis and pressures within the asylum system”.
Home Secretary Suella Braverman said: “Our impact assessment shows that doing nothing is not an option.
“We cannot allow a system to continue which incentivises people to risk their lives and pay people smugglers to come to this country illegally, while placing an unacceptable strain on the UK taxpayer.”
The UK is spending £6m a day to house asylum seekers in hotels.
Last year more than 45,700 people made the dangerous journey across the Channel in small boats.
Prime Minister Rishi Sunak has made stopping the crossings one of his five key priorities, with the bill central to the government’s plans to achieve this aim.
Rwanda is currently the only country the UK has a deal with to relocate migrants to but no flights have set off yet.
The High Court ruled in December 2022 that the scheme is legal, but that decision is facing further challenge in the courts, with a judgement due on Thursday.
