Members of the Public and Commercial Services Union at the Old Tree Court job centre in Plymouth will stage a strike on the last two working days before Christmas.
The industrial action is in protest of plans to transfer some of the 200-strong staff to other offices.
The union, which successfully campaigned for the job centre to stay open, fears the plans will lead to redundancies.
The Department of Work and Pensions says the changes will mean a more efficient, cost effective service. It also says it is committed to finding staff alternative employment.
The strike will take place on Thursday 21 and Friday 22 December.
Job Centre staff at a call centre in Bristol will strike today as part of action by the Public and Commercial Services Union. They say working conditions in call centres are oppressive and have unrealistic targets. 6,000 union members across the UK are taking part in the strike.