Greens call for superannuation tax change

The Australian Greens have asked Treasury to provide costings on a proposed change to the way superannuation is taxed.

Greens leader Bob Brown said he had spoken to Treasurer Wayne Swan about raising the tax rate on superannuation for high-income earners and cutting it for those on low incomes.

Senator Brown said that at present about $30 billion in revenue was foregone because of the tax break on superannuation - and will rise to $40 billion in four years.

"Half of those tax breaks go to the 12 per cent of top income earners and there's no real advantage for lower income earners in that set-up," Senator Brown told reporters in Canberra on Monday.

"So instead of a general 15 per cent tax break, the tax break would be 15 per cent off the marginal tax that the income earner pays."

He said the change would still provide an incentive for high-income earners but give a better deal to lower income earners.

Senator Brown said it was possible the measure would be "better than cost neutral" and help the government restore the budget surplus.