Computer staff at the Driver and Vehicle Standards Agency have launched a month-long strike in a dispute over pay.
Members of the Public and Commercial Services union (PCS) based in Nottingham and Swansea are in dispute over out-of-hours working payments, overtime pay and a claimed lack of consultation from management.
The DVSA deny the strike is about pay.
The union said the strike, which started on Thursday, will affect maintenance of IT systems used to book and allocate driving tests, incident management and training of new staff.
However, the DVSA also denies this is the case, saying the strike would affect only a few staff. It also denies the union's claim that the strike will affect maintenance of IT systems used to book and allocate driving tests.
The teams who do this work are unaffected by the strike, according to the agency.
The DVSA said the strike action was "unnecessary".
The DVSA spokesperson said a total of ten staff members went on strike on the first day of the strike (Thursday 22nd). All of those staff members were in the DVSA office in Nottingham.