Driving tests are set to be hit with examiners staging walkouts next month in the first wave of industrial action by civil servants.
The Public and Commercial Services union announced dates for the action saying it will cause "a massive amount of disruption".
The union said the Driver and Vehicle Standards Agency will join rural payment officers at more than 250 sites across the country next month.
Striking workers at the DVSA will include driving examiners, call centre staff, and local driving test managers, the PCS said.
The Rural Payments Agency meanwhile is responsible for making payments worth around £2billion a year to support the farming and food sector.
These organisations will take part in a series of rolling strikes on a regional basis from December 13 to January 16.
It comes after around 100,000 members of the PCS union voted for strike action earlier this month in a dispute over pay, pensions and job security.
The DVSA and the Rural Payments Agency are the first of 124 Government departments to announce when industrial action will take place.
Mark Serwotka, the General Secretary of the PCS, said: "This is the first wave of the hardest-hitting industrial action the Government will have faced in decades and will cause a massive amount of disruption.
"The government, which has spent years turning a blind eye to our pay demands, will no longer be able to ignore us.
"Our members are proud of their work, so it's not easy for them to take action they know will affect the very people they came into the job to serve.
He added: “But the government has given them no option. Their pay has fallen far below inflation and many of our members – the government’s own workforce – are forced to use food banks because they can’t afford to eat.
"The government is in the position to stop these strikes by putting money on the table.
"Ministers must know we will not stop until our demands are met and our members receive the decent pay rise they need to get them through the cost-of-living crisis and beyond.”
The union is set to announce dates for other departments, including the Home Office and Department for Work and Pensions, over the next few weeks.
A government spokesperson said: “We regret this decision. We greatly value the work of civil servants across the country, but the PCS Union's demands would cost an unaffordable £2.4 billion at a time when our focus must be on bringing down inflation to ease the pressure on households across the country, protect the vulnerable and rebuild our economy.
“Discussions will continue, but we can provide reassurance that we have comprehensive plans in place to keep essential services running and to minimise disruption if these PCS strikes do go ahead.”
