Treasurer Scott Morrison considers super reform options

Treasurer Scott Morrison says he isn't ruling anything in or out as he seeks to inject more flexibility into the superannuation system.

The government wants to close the retirement savings gap and reduce reliance on pensions later in life.

Mr Morrison said it had been known for some time that women were prone to having their work patterns disrupted, placing them "behind the curve" in trying to build superannuation savings.

One option under consideration would possibly lift the tax cap on contributions to allow working mums to top up their super when they return to work without copping a tax penalty.

"We are having a good look at it," Mr Morrison said.

Opposition Leader Bill Shorten is pushing Labor's proposal for zero tax on superannuation for those earning less than $37,000.

"The tax they pay on their superannuation is actually higher than that tax they pay on their normal income which they spend. We think that's a perverse system. It's unfair," he told ABC radio.

Mr Shorten said that affected 3.5 million people, 60 per cent women.

He said the government should also consider increasing the superannuation guarantee rate, now set at 9.5 per cent.

"Will he (Mr Turnbull) back removing the taxpayer-funded subsidies that the really, really, really wealthy, people who already have millions in their superannuation currently receive," he said.