Union chiefs have announced their first in a wave of strikes at the Department for Work and Pensions as workers walk out for two weeks over Christmas.
Around 200 benefits staff will down tools between December 19 and 30 at three Jobcentres in Liverpool and a back office in Doncaster.
The union expects it to disrupt benefit “conditionality” interviews which would normally lead to sanctions.
The Public and Commercial Services union strike is on nine days - December 19, 20, 21, 22, 23, 24, 29, 30 and 31.
PCS officials said the “targeted” action would cover only a fraction of the union’s DWP members, but more dates are likely to follow in its bid for a 10% pay rise.
It comes after more than 100,000 civil servant members of the PCS voted for strike action at 126 government bodies.
The union has already announced 12 days of rolling strike action at National Highways over Christmas and New Year, and a month of strike action across 250 sites of the Driver and Vehicle Standards Agency and the Rural Payments Agency.
Dates for the Passport Office and Border Force - where troops could be drafted in to cover for striking workers - are likely to be announced in the coming weeks.
PCS general secretary Mark Serwotka said: “Our members have been plunged into ever-increasing depths of poverty.
“They shouldn’t have to rely on foodbanks to feed their children or be forced to make the choice of either working from home because the journey into work is too expensive or working in the cold under blankets because the cost of heating is too expensive.
“It’s a disgrace that our members in the DWP – the government’s own employees – are claiming the benefits they pay out to others.”
The DWP has been contacted for comment.
It came as the Fire Brigades Union opened its first ballot for firefighter strikes over pay in nearly 20 years.
Up to 33,500 firefighters and control staff will vote between now and January 30 after rejecting a 5% pay offer.
FBU general secretary Matt Wrack said: “Strike action will always be a last resort. But we are running out of options.
“Many firefighters and control staff are desperate. Some are struggling to afford to live. It is a dreadful and very serious state of affairs.
“We are doing everything we can to secure a decent offer. We have held talks with and written letters to many different parties. But no such pay offer has been forthcoming."
A DWP spokesperson said: “We greatly value the work of our staff but the PCS Union’s demands would cost the country an unaffordable £2.4 billion when the focus must be on bringing down inflation to ease the burden on households, protect the vulnerable and rebuild our economy.
“Benefits, the state pension and child maintenance payments are paid automatically and people who rely on that support will continue to receive it.”
