PCS members working in the new Universal Credit benefits system will strike for two days from 20-21 July over increasingly oppressive working conditions.
Staff voted by 84% to strike about a lack of resources, an oppressive management culture, inadequate training, hard to reach targets and staff shortages.
The strike involves over 1, 500 workers at two sites in Bolton and Glasgow, where more than half of all universal credit staff are employed.
PCS represents around 80% of staff at the centres that process claims to universal credit and take enquiries from claimants by telephone and online.
The dispute also includes the imposition of new conditions, including predetermined start and finish times and severe restrictions on flexible working.
The two-day strike will be followed by industrial action short of a strike until mid-August.
The union has not ruled out balloting its members at the other universal credit sites in Bangor, Basildon, Dundee, Makerfield and Middlesbrough.
PCS general secretary Mark Serwotka said: “The introduction of universal credit has been a textbook example of how not to reform essential public services, and the DWP’s handling of every aspect of it has been disastrous.
“These harsher working conditions must be withdrawn, they simply heap more pressure on staff who have battled against poor IT, inadequate training and a lack of resources.”