Private contractors are scheduled, to take over the call centres, which deal with tax credits queries, from January next year as a trial exercise.
Seven out of 10 members of the Public and Commercial Services Union, which represents 21,000 staff at the central government department, voted to walk out, while a further 86% also agreed to get involved in other forms of industrial action.
Mark Serwotka, the PCS’ general secretary, said: "Instead of cutting jobs and selling off our public services for private profit, ministers should be investing in their staff and ensuring they have the resources they need to help the public who rely on them. This strike vote shows tax workers have very real fears about allowing the private sector in to do their work and what this would mean for the security of the sensitive information they handle."
The union also called on HMRC to stop further planned cuts in jobs in a department that has already lost 30,000 posts since 2005.