It would cost £63,000 more to send a migrant to Rwanda or another “safe country” than to keep them in the UK, the government has said.
An economic impact study of the Illegal Migration Bill, which is pending in Parliament, revealed a gross cost of £169,000 to relocate an individual.
But there would be cost savings of around £106,000 as they would no longer need housing support.
The government said the policy would also have a chilling effect.
The Home Office assessment said no costs would be incurred if an individual was deterred from entering the UK illegally.
He said the potential savings were “very uncertain”, but gave an estimated figure of between £106,000 and £165,000 per individual.
The bill aims to stop people crossing the English Channel in small boats by preventing anyone arriving in the UK illegally from seeking asylum.
Instead, they would be detained and returned, either to Rwanda or to another “safe country”.
Home Secretary Suella Braverman said: “Our impact assessment shows that doing nothing is not an option.
“We cannot allow a system that encourages people to risk their lives and pay smugglers to come to this country illegally, while imposing unacceptable pressure on the British taxpayer.”