PCS members working at the Driver and Vehicle Licencing Agency (DVLA) have voted for industrial action over continuing Covid health and safety concerns.
The ballot returned a 71.6% vote for strike action on a turnout of 50.3%.
The DVLA office in Swansea suffered the worst Covid workplace outbreak in the UK but over 2,000 staff have been going into the workplace every day.
The union has repeatedly called for a huge reduction in footfall at DVLA, pointing out that during the first lockdown, only 250 people were in the workplace carrying out essential duties.
PCS general secretary Mark Serwotka said: “This result is a damning indictment on DVLA management in their abject failure to keep staff safe.
“Our members have sent a loud and clear message that they are not safe at their place of work. The strength of feeling amongst staff comes as no surprise, given the management’s disregard for the safety of their workers.
“Our members have been forced into this position and industrial action will take place unless management immediately implement all necessary changes to ensure staff are safe at work.”