Driving test examiners are voting on whether to strike in a dispute about job cuts and office closures.
About 1,800 examiners and admin staff employed by the Driving Standards Agency will take part in the ballot, with results expected in a few weeks.
The PCS union said members were angry at plans to close offices in Edinburgh, London and Birmingham, which they say will lead to 80 job losses.
But Driving Standards Agency chief executive Rosemary Thew denied suggestions that 80 jobs were earmarked to go.
“We have given a commitment to work with the union throughout the summer to look at what work may be available to those staff affected by these proposals,” she said.
PCS general secretary Mark Serwotka said: “Members are understandably angry and this ballot gives them an opportunity to send out a clear message that they will not accept the plans.”
The union says there is also anger among members about the £300,000 spent on a consultants’ report which recommended the changes.