Wage and salary earners paid out $1.7 billion in "stealth" tax last year after inflation increases pushed workers and their pay packets into higher tax brackets, according to advice to the Tax Working Group.
Officials have warned the public could see the money as having come through a stealth tax and Government may want to change it as a "value judgment".
They have also said if the Government did change tax rates it would increase transparency and account for inflation but money would need to be found to pay for public services.
The $1.7bn quoted by officials is the equivalent of the budget for our entire police force.
The extra tax was scooped up after the former government left tax brackets largely unchanged during its time in office, with the highest tax bracket fixed to kick in at $70,000.