Managers at the National Ambulance Service (NAS) have been instructed not to bring their staff vehicle home when out of hours until a dispute over benefit-in-kind has been resolved.
The instruction was confirmed by the HSE.
In a statement, it said: "The HSE must comply with Revenue Commissioner regulations in relation to what in this case is the potential personal use of publicly owned vehicles. All HSE employees are covered by these rules."
It added: "The HSE National Ambulance Service has identified that the number of incidents responded to by vehicle users outside of working hours is minimal.
"Response times carried out and reported on by the NAS through HSE service plan performance targets relate to emergency ambulances or vehicles capable of transporting patients only."
The statement concluded: "As a public body, the HSE cannot support the use of publicly owned emergency vehicles for purposes that the Revenue Commissioner considers potential personal use or benefit."
Sinn Féin health spokesperson David Cullinane has described the decision by the NAS to cease allowing senior officers to bring a vehicle home, out of hours, as "reactionary and premature".
He said: "Every effort must be made to find a resolution between senior management and the director of the NAS."
Mr Cullinane added: "Senior officers dispute that the cars are being used for personal use. In fact, they assert that the real benefit of having a car at home is that they can respond to call outs if required.
"This decision may lead to senior officers no longer being in a position to rapidly respond to a call out of hours when required."
