Civil and public servants working in most government departments and agencies will be on strike from 1pm for half a day on Friday 5 April.
Around 55,000 PCS members in HM Revenue and Customs will hold a half-day strike on the morning of Monday 8 April.
This is designed to disrupt the start of the new tax year and the introduction of 'real time information', whereby employers who operate PAYE are required to notify HMRC immediately every time they pay their staff and make deductions.
The union's 12,000 members in the Home Office, UK Border Agency and border force will also be on strike all day on Monday 8 April in response to the department telling staff they would be docked a full day's pay even if they only walked out for half a day on Friday.
These walkouts all form part of a three-month programme of industrial action and protests, which began with a national strike on budget day on 20 March.
The union has asked for talks over cuts to civil service pay, pensions and terms and conditions, but the government has refused to negotiate. PCS general secretary Mark Serwotka said: "We said our budget day strike was not a one-day protest and this long weekend of walkouts is the next step in a series of strikes 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."