Thousands of Revenue and Customs workers will go on strike tomorrow in the latest phase of months of industrial action by civil servants in a row over jobs, pensions and terms and conditions.
Members of the Public and Commercial Services (PCS) union will stage a half-day walkout until lunchtime, which officials said will disrupt the start of the new tax year.
Picket lines will be set up outside offices across the country, including call centres, processing offices and the face-to-face inquiry centres.
The union, which has over 50,000 members in HM Revenue and Customs, said many staff will hold "walk-ins" at 1pm so they all go back to work together in a show of solidarity.
The strike follows a walkout by PCS members in other government departments, courts, driving test centres and museums on Friday as part of a three-month campaign over cuts, which started with a national strike on Budget day, March 20.
A 24-hour strike in the Home Office and UK Border Agency planned for tomorrow was postponed after a legal challenge, but will now be escalated to a week-long series of walkouts across various parts of the department in a fortnight's time.
PCS general secretary Mark Serwotka said: "These strikes are part of an ongoing campaign of industrial action and protests to cause disruption for the Government at key times and put pressure on ministers who are refusing to even 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."
The PCS has held talks with other unions about co-ordinating industrial action against the Government's austerity measures and spending cuts.
The TUC conference voted last year to discuss the practicalities of holding a general strike, and the issue is set to be debated at a meeting of the its general council later this month.
Asked if he was talking with other union leaders about a general strike, Mr Serwotka told Murnaghan on Sky News: "We are definitely having a discussion about generalised strike action.
"More imminently than that we are having the beginnings of a much more detailed discussion between unions who have real industrial issues in front of them now about co-ordinating their efforts to ensure that our attempts to fight back and defend our members is more effective."
He added: "My own opinion is that what the Government is doing is getting so increasingly unpopular that even a 24-hour strike involving millions of people across the economy would be an incredibly important moment. It would show that people can fight back and say we don't just have to accept our lot."Suggest a correction