Inland Revenue has been criticised over changes to how carparks provided by employers are taxed.
A partner at PWC, Elle Ward, said the present rules are untidy, and changes are needed.
But she said plans to impose different rules depending on whether firms are located are bad policy.
Fringe benefit tax will apply to businesses outside Wellington and Auckland central business districts in only very limited cases.
For Auckland and Wellington businesses, she said, the planned changes are very complicated and in some cases will require daily calculations.