Gillespie explains his GST tax modelling

Mr Morrison said state and territory governments were negotiating in “good faith” with the Turnbull Government, but criticised the ALP for refusing to do the same.

Labor is demanding Scott Morrison come clean on his GST intentions after the treasurer flagged the prospect of “pretty significant” tax changes.

But federal Labor could end up politically isolated after the next election if it lost and continued to oppose change, amid signs Labor state premiers could shift.

“What Malcolm Turnbull seems to do is be promising everything to everyone, but of course what we known when it comes to an increases in the GST is that it is regressive”, she told Sky News.

“If they are going to do that, be up-front with the Australian people”, Mr Bowen told reporters in Sydney.

“I’m not advocating just a tax grab”.

Mr Turnbull said on Monday that his preference was for an election in September or October, which means could be the centrepiece of the May budget.

The government had not yet decided on any particular tax reform, such as increasing the GST, he said.

“We have to make absolutely clear that any changes to the tax system or transfer payment system are ones that are fair, that are seen to be fair across the board”.

Malley says CPA Australia has done modelling into how much revenue the government could raise if it raised the GST to 15%.

Mr Morrison reiterated everything was on the table during what he labelled a “discovery phase” with the states and territories. “I have to run a health system”, the SA premier said.

“Nobody wants to say it out loud because it’s unpopular to say it”, Mr Weatherill said.

Mr Weatherill chipped his federal Labor counterparts, saying he had yet to see from them a proposition that would fill the funding gaps facing the states.

However, he would not specifically back a proposal to increase the GST to 15 percent.

“Our first priority remains addressing the looming fiscal gap faced by all states and the commonwealth over the next 20 years as a result of our growing health funding needs”, she said.

But Sen Sinodinos said the move would require the states to be “at least neutral” on the issue – an unlikely task, given Victorian Premier Daniel Andrews said yesterday he would not support any increase.

This would be enough to abolish insurance taxes, stamp duty on motor vehicles and 80 per cent of conveyancing stamp duty.

“Any remaining additional GST revenue is returned to households through personal income tax cuts and welfare payments”, KPMG says.

The treasurer, Scott Morrison, on Monday confirmed treasury had modelled various GST reform options for the states, and that work had been the basis of a weekend media report citing firm government plans to increase the GST to 15%.

A total of $130 billion in revenue would flow to the government’s coffers in 2017-18 under the GST increase, amounting to an extra $65.6 billion, according to the non-partisan Parliamentary Budget Office (PBO).