Some Home Office staff are getting an inflation-busting 9% pay rise, the department has confirmed.
The union representing civil servants, PCS, welcomed the deal, which is nearly double the 5% agreed for most civil servants.
The pay boost is meant to improve staff retention and morale, which is the lowest in the civil service.
But Conservative MP Neil O'Brien said the pay hike would "stick in the craw" of people worried about immigration and crime.
The BBC understands the pay rises will be backdated to the start of July and will range from 6% to 9.1% for executive officers working outside of London.
Inflation is running at 2.2%, according to the latest figures.
But the PCS union said its members "deserve rises significantly above inflation to reclaim pay that we have lost through years of below-inflation rises".
The Home Office's most recent annual report showed the cost of hiring temporary agency staff had tripled on the last two years to more than half a billion pounds, most of which was spent on dealing with illegal immigration, as well as the now-cancelled Rwanda deal.
A Home Office spokesman said the pay rises were in line with the civil service pay remit guidance.
He said: "This year’s pay guidance recognises the hard work and vital importance of all our staff and is broadly in line with others in the public sector.
"One relatively junior grade in a particular region has received the higher amount to bring them into line with their peers."
PCS general secretary Fran Heathcote said she would continue to push for a "fair and sustainable long-term pay settlement" to make up for "many years" of below-inflation pay.
She said: "We have made progress in negotiations with the Home Office and we welcome the fact that the final offer would deliver increases for the admin and executive grades that are above the 5% headline figure in the civil service remit.
"We believe this is the best award that can be delivered through departmental negotiations alone."
However, critics have questioned whether the recent performance of the Home Office staff justified a bumper pay rise.
The move comes as the number of migrants who have crossed the Channel in small boats so far this year topped 29,000, approached the total for the whole of last year.
O'Brien said: "I have no problem with people being rewarded for good performance.
"But with massive numbers crossing the channel, crime clear-up rates low and dangerous people getting let out of jail, this large pay rise will stick in the craw of a lot of people."