The Government denies it has reneged on a promise about a tax on car parks.
A tax is under consideration despite Prime Minister John Key saying in 2005 that his party would not apply a fringe benefit tax to employee car parks if elected.
During parliament's Question Time, the Labour Party asked why Mr Key's pledge had been broken.
In reply, senior Cabinet Minister Steven Joyce said much has changed in eight years.
A lobby group claims the tax would add $1500 a year to the cost of a carpark provided on an employer's own premises and $2400 for a space paid for in a commercial carpark.
Mr Joyce doubts the accuracy of those figures, but says the tax could be reconsidered if compliance costs are deemed too high.