People applying for a visa to visit the UK are to be charged £5.48 to receive responses to customer service emails.
The Home Office announced the new fee as part of an outsourced contract.
It says that the credit or debit card charge will reduce the "significant" cost to taxpayers of overseas inquiries.
But immigration rights groups said visa fees were already very high and the change would result in more rejected applications.
Chai Patel, legal and policy director at the Joint Council for the Welfare of Immigrants, said: "The more difficult people find it to make applications, the more likely they are to make mistakes and have their applications returned - only adding to work and costs for the Home Office, which is already critically overstretched and under-resourced."
The cost of a UK visa varies from £89 for a 6-month standard visitor visa to £3,250 to settle a dependent relative.
Figures from the Office of National Statistics show there were 2,978,018 applications for visas in the year up to March 2017, including tourists, workers, students and family members.
A Home Office source said the new contract with Sitel UK, including charges for inquiries over email or phone, would help to make the service "cost-neutral" for the taxpayer.
The contract also reduces the language services from 20 to eight, with Punjabi and Urdu among those being cut.
The Home Office says 80% of calls and emails are made in English and only 4% are in the languages which will no longer be offered.