High income earners would pay more tax on superannuation contributions and lower income earners would get a reprieve under a scaled model the federal government is considering.

Treasury officials are briefing industry players on a plan to charge super contributions at 20 per cent below an individual’s marginal tax rate, the Australian Financial Review reports.

The model would replace the current flat rate of 15 per cent tax on contributions for anyone earning less than $300,000 and would mean anyone on $150,000 or more can expect an increase in their super contribution tax rate.

Assistant Treasurer Kelly O’Dwyer says while there are lots of options being discussed in the media, it wasn’t the government’s option.

“The government’s considering what we need to do overall with our tax system,” she told Sky News.

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Responding to a report in The Australian that a lifetime cap on super was being examined by Treasury, Ms O’Dwyer said there were already caps on what people could contribute.

“This idea that people can amass multi-millions of dollars in their superannuation funds is just simply not correct,” she said.

Opposition Leader Bill Shorten said superannuation tax concessions for high income earners were unsustainable.

He encouraged the government to back Labor policy of 15 per cent tax on the super accounts of retired Australians which earned more than more than $75,000 in a year.

Labor also wants to reduce the income threshold for the 30 per cent high-income superannuation charge from $300,000 to $250,000.

“I say to Malcolm Turnbull and the Liberals, Labor has a good idea and you’re welcome to take it up,” Mr Shorten told reporters in Canberra.

Independent senator Jacqui Lambie told reporters she is yet to see any proposal but she supports increasing the super contributions tax for the rich.

Greens MP Adam Bandt said the minor party was prepared to discuss putting a lifetime cap on voluntary super contributions.

“It’s clear a small number of very wealthy individuals have been using it, at the end of their working life, to minimise tax,” he told reporters.