In the strongest hint yet that the Turnbull government plans to swap income tax for more goods and services tax, the Treasurer Scott Morrison has promised that any switch won't increase the total tax take.

"Our goal is to deliver a better tax system, with a better mix," he told the Melbourne Institute economic and social outlook conference.

"We will achieve stronger revenues by having a stronger economy where Australians and Australia earn more," he said. "Not by placing a greater tax burden on our economy and on Australians."

His guarantee came as Labor endorsed a study by the National Centre for Social and Economic Modelling and the Australian Council of Social Service that found that a switch from income tax to a higher or broader goods and services tax would make the lowest-earning 60 per cent of households worse off and the top 40 per cent better off.

"This vindicates everything Labor has been saying about the GST," the shadow treasurer Chris Bowen said. "Are we really going to increase the GST each time the nation suffers bracket creep? Is that the best we can do?"

At the same time leading economist Ross Garnaut attacked calls for a cut in the company tax cut, saying they owed more to lobbying than rigorous analysis.

Prime Minister Malcolm Turnbull said any changes to the tax system had to "be fair".

"A reform package must, at the very least, raise the revenue we need, share the burden fairly across the community and do so in a way that incentivises employment, innovation and investment," he said.

"Fairness is absolutely critical. Any package of reforms which is not, or is not seen as fair, will not and cannot achieve the public support without which it simply will not succeed."

Mr Morrison said Australia relied more on income tax and company tax than any other Organisation for Economic Co-operation and Development member other than Denmark.

"As a result, next year the average wage earner is forecast to move into the second highest tax bracket," he said.

"Around 300,000 Australians are expected to move into the second highest tax bracket over the next two years. If there were no tax cuts for 10 years, nearly half of all taxpayers will be in the top two tax brackets."

Income tax was "a silent tax", whereas the goods and services tax was openly displayed.

"When young people go to the automatic teller machine to draw out their cash they do not see, as they do with the GST on their sales receipt, the 19 cents or the 32.5 cents or the 30 cents or the 37 cents or the 45 cents that has been deducted," he told the conference.

"There is not the same transparency or awareness of just how much tax they are paying. Income tax is too often out of sight.

"I want Australians to be able to earn more, but I also want them to take home more from what they earn. I would prefer to leave it to them how they choose to spend, save and invest the money that they earn."

However Mr Morrison said the government had not yet made a specific decision about the GST, and would not be "rushed to failure".

Whatever was decided would be put to the next election, he said.

Business Council president Catherine Livingstone said while cuts to personal income tax were of critical importance, nothing would stimulate the economy more than a cut in the corporate tax rate.

"These income tax rates really matter, whether personal or business," she said. "If there is no growth dividend from tax reform it will be a missed opportunity."

Professor Garnaut lambasted calls for a cut in the company tax rate, saying the Treasury modelling used was flawed and would not withstand scrutiny.

"The case is usually based on a Treasury paper that is built on a model that includes complete competitive and open capital and goods and services markets," he told the conference.

"It is hard to see how it can be reasonably applied to an economy in which a majority of corporate profit are in sectors in which monopoly, regulatory and resource rents represent a pretty high proportion of the profits."

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