Speaking at the Tax Institute conference in Melbourne on Thursday, the head of Treasury's tax analysis division, Roger Brake, said that the department was well aware that community engagement was "critical" if the government was going to deliver tax changes such as an increase in the GST and broadening of the base and cuts to the company tax rate.

Treasury was also aware that every change involved tradeoffs and that those tradeoffs could be hard  for the public to digest, he said.

"There are a lot of difficult and controversial choices," said Mr Brake, who is now a part of Treasury's Tax White Paper Taskforce, which is assisting the government in narrowing down recommendations for the options paper by the end of the year.

The tax "green paper" will summarise reform options based on almost 900 submissions made as part of the tax white paper consultation process.

"More often than not there's tension between efficiency, equity and simplicity when you develop tax policy," Mr Brake said.

The government needed to consider the tax system as whole because "there will always be leakages, and positive and negative flow-on effects" from the reform process, he said.

Without selling the case for change, the entire process would stall.

"Successful reform must have broad community support," Mr Brake said.

Treasury's here to help

Ultimately, it was up to government to decide which options to put to the public, Mr Brake said.

But "Treasury can assist" in helping with the pitch to the community.

The tax white paper had identified "strong support for broad reform of the system", he said.

"Very few people think the tax system is perfect and there's no need to change anything," Mr Brake said.

The consultation process had identified broad themes including an economic case for broadening the GST base and lifting the rate, lowering the company tax rate to 25 per cent, reducing personal tax rates, and getting rid of inefficient state taxes such as stamp duty and insurance levies.

There was also support for reducing existing superannuation concessions that were inequitable, he said.

But most submissions were against changing Australia's dividend imputation system, which allows franking credits to be dished out to shareholders and self managed superannuation fund members.

A company tax cut can be affordable

Mr Brake said if Australia didn't act fast on issues such as company tax, it would fall behind other countries which had already moved to cut their tax rates.

The head of Treasury's revenue group, Rob Heferen, has also publicly thrown his support behind cutting corporate tax.

"The world is an increasingly competitive place," Mr Brake said. "As other countries improve their [tax] policy settings we can expect they will attract more foreign investment."

A change to the company tax rate was "not necessarily an easy argument for the wider community to understand", he said.

But "​company tax matters because it affects the level of investment in Australia and in turn the stock of capital and the productivity of workers".

Treasury had estimated that a reduction in the company tax rate to 25 per cent, done alongside a shift to more efficient taxes on labour and/or consumption (in the form of the GST), could add 1 per cent ot Australia's GDP over time.

Wages would also be boosted, and ultimately, the productive gains would outweigh the cost of reducing the company tax rate from 30 to 25 per cent.

The second-round benefits of such reform would fund about 40 per cent of the direct revenue cost of the company tax cut, Mr Brake said.