Civil servants are to stage a strike on Budget day to launch three months of industrial action in a worsening row over pay, pensions and working conditions.
The Public and Commercial Services union said almost 250,000 workers will take part in a rolling series of walkouts and protests as it steps up its campaign against cuts.
A 24-hour strike will be held on March 20, the day Chancellor George Osborne presents the Budget to Parliament.
Further national stoppages will be held, of varying durations and targeting different parts of the civil service, with dates to be announced at a later stage.
Other forms of disruptive industrial action short of a strike will also be held, and the PCS said it will seek to co-ordination with other unions on pay and pensions.
PCS general secretary Mark Serwotka said: "This is not a one-day protest, this is the start of a rolling programme of walkouts and disruptive action to put pressure on a government that is refusing to talk to us.
"Civil and public servants are working harder than ever to provide the services we all rely on but, instead of rewarding them, the government is imposing cuts to their pay, raiding their pensions and trying to rip up their basic working conditions.
"We warned more than two years ago that austerity wouldn't work and we were right. There is an alternative to cutting the living standards of hard-working public servants and our campaign is designed to make the case loud and clear."