"Participants that mention the mining tax or the GST won't have their microphones cut off or be thrown out by bouncers." Business bodies including the Australian Industry Group want the forum to consider an increase in the GST rate and a broadening of its base as a way of getting rid of inefficient state taxes. The consumption tax has remained untouched at 10 per cent since its introduction 11 years ago, but the government has ruled out pursuing changes to it. Mr Swan made it clear the government would not be reassessing that approach. "It's just commonsense that the government isn't going to hit the reset button on policies that we've already consulted on extensively over many months or even years," he said.

"Likewise, we're not going to revisit policies that we've ruled out in the interests of business and community certainty." Liberal frontbencher Greg Hunt says Prime Minister Julia Gillard should use the forum to pledge to take her unpopular carbon tax to an election. Mr Hunt made it clear the coalition also had no plans to increase the GST. "That is express, clear and absolute," Mr Hunt told Sky News. "It's not on our agenda, in our plans or our policy." But prominent economist Saul Eslake says the major parties should be willing to compromise on the GST.

"The GST has almost become the Lord Voldemort of the tax debate in Australia - it's something that can't be named by either side," Mr Eslake told Network Ten, referring to the villain from the Harry Potter books. "The exemptions from the GST favour the rich disproportionately and are becoming increasingly costly as an erosion of revenue." Mr Swan is playing down what the forum is likely to achieve. He says it is not geared towards reinventing the tax system overnight or achieving some kind of grand bargain. "It's about the government listening, not talking," the treasurer said. Mr Swan is also warning that tax reform is more difficult in the current volatile global economic environment.

"It means we can't just talk about cutting or abolishing certain taxes without looking at the other side of the equation: things like closing loopholes and getting rid of unnecessary tax expenditures," he said. The ACTU says the forum should focus on how to deliver a fairer tax system. "Under the Howard government, taxes on high-income Australians were cut far more than in almost all other developed countries," ACTU secretary Jeff Lawrence said in a statement. "The result over the past decade is that the income tax system has become flatter and far less progressive than it should be in a fair and equitable society. "We must now turn this around."

Queensland Treasurer Andrew Fraser said on Sunday he would use the forum to call for reform of tax offsets for Australians who live in remote and regional areas. Loading The forum is to be held in Canberra on Tuesday and Wednesday. AAP