Van drivers using the company vehicle for personal mileage are to be hit by "crippling" new tax rules, Coventry accountants Pilley & Florsham have warned.
And, said partner Laurence Moore, it is the responsibility of employers to forewarn them.
Under the new rules, which have provoked mounting concern, bosses and drivers will have to demonstrate that the firm's vans are not being used for private use - or the drivers will be paying hundreds more pounds in tax each year.
Under the current rules, the private use of a company van - other than to and from home - is deemed to be an employee benefit worth £500 a year - £350 if the van is more than four years old. But, the following year, the benefit in kind charge will rise to £3,000, and an extra £500 where fuel is provided.
Mr Moore said in such cases the onus was on the employer and driver to demonstrate the van was not being used for private trips.
"The best way to achieve this is for employers to issue written warnings to drivers, prohibiting such use," he said. "This can cause a problem. An employee might feel aggrieved with the burden of a company vehicle - which is used strictly for work - sitting on his drive all week.
"And the employer could face just as much inconvenience if the employees decided not to take the vehicles home with them, leaving the business premises clogged and congested with numerous company vans. In fact, I would imagine some firms could find this new tax rule crippling."