PCS will ballot Department for Work and Pensions members on taking strike action over pay in the new year.
The union has announced its DWP group will conduct a statutory ballot of members in January and February in an escalation of its dispute over pay.
It comes after DWP staff indicated support for industrial action last month over pay concerns in a consultative ballot held by PCS.
PCS dismissed DWP’s “unacceptable” pay deal for staff in August, asking the department to reopen pay talks on the grounds that it does not do enough to boost wages of staff at the lowest grades.
It said the department's use of the 3.25%-plus-0.5% pay remit for 2025-26 had failed to address "serious issue of chronic low pay”, as the department had used the additional 0.5% allowed for by the remit to address anomalies in higher grades.
The union’s DWP branch said the department has refused to reopen pay talks and has “dismissed” employees’ concerns.
PCS general secretary Fran Heathcote said: “The functioning of the welfare state depends on our members’ hard work and good will. But they have had enough of poverty pay. DWP has some of the lowest-paid members in the civil service, paid well below the market value for their skilled work.
“PCS members’ ringing endorsement of strike action shows there’s a strong determination to fight. All they want is fair pay in recognition to the vitally important service they deliver to some of the most vulnerable people in society."
The union said a recent survey of its members in the DWP had found up to 20% of respondents were claiming in-work benefits and almost 14% of respondents reported using food banks for extra support.
DWP has been approached for comment.