The Labour Party says it would support a rise in the threshold for the top tax bracket in a reform of the tax system.
A report produced by the Tax Working Group includes recommendations to raise GST and cut the top tax rate.
At present, people in the top bracket pay 38 cents in the dollar for earnings more than $70,000 p/a.
Labour leader Phil Goff says lowering the rate of tax is one option being considered by the Government.
But, he says, allowing people to earn more before they pay the top tax rate is a move Labour would support.
Mr Goff says Labour will not support moves to increase GST if only the top tax rate was to be reduced.