PCS members have voted by a massive majority to back the union's campaign against cuts to public services, jobs, pay and pensions.
In a national ballot 90% rejected changes to the civil service redundancy scheme – and 96% supported the union's national campaign, ‘There is an alternative’.
More than 80,000 people voted in the ballot – a turnout of 32%.
PCS starts a legal challenge next week.
The union has called on the government to reopen negotiations to agree a new scheme that protects members’ rights.
Meetings will be organised in workplaces covered by the CSCS so members can discuss the next stage of the campaign.
Across the country PCS branches are taking part in anti-cuts campaigns and putting forward the argument that there is an alternative to austerity.
PCS members are urged to attend the trade union organised ‘March for the alternative’ on Saturday 26 March, with their friends and family.