The RHA has raised concerns that many operators are unaware of the costs they'll be hit with when the apprenticeship levy comes into effect next April.
Any company with payroll costs above £3m will be required to pay the equivalent of 0.5% of that cost into the tax. The association predicted this would hit companies operating 80 or more vehicles.
RHA deputy policy director –for employment and skills, Colin Snape, said: “The apprenticeship levy is not only relevant to very large companies.
"It has become clear that while most firms know that there are new industry apprenticeships, many are unaware that at the same time they are going to be taxed."
Snape added that while the levy was "unwelcome", companies could avoid losing the money by ensuring they claim it back as funding for apprenticeships.
“While the levy is unwelcome, the RHA is working to ensure the industry takes full advantage of what should be an important new opportunity for firms of all sizes to take better control of the recruitment and training of staff,” he said.