New modelling shows proposed changes to the GST would raise the same amount of revenue as a carbon tax, but cost Australian households about three times as much.

Analysis from the Parliamentary Library shows the Government would raise about $14 billion a year by broadening the base of the GST or increasing the tax to 12.5 per cent.

That would cost households about $31 a week compared to a carbon price of $28 a tonne that would cost households $11 a week.

Greens treasury spokesman Adam Bandt said the results showed bringing back a price on carbon would be fairer than any increase to the GST.

"If you want to raise additional revenue, who should pay?" he said.

"Should it be the big polluters with a smaller proportion of it falling onto households? Or do you want to do what the Liberal government is proposing, and shift the burden downwards away from those who can afford it?

"You can do it either by raising the GST which will lift the prices of almost everything we buy, and put an extra $31 burden onto households.

"Or you do it with a carbon tax which will lift costs to household by about $11 a week — so about a third — and cut pollution as well."

Opposition Leader Bill Shorten on Friday said Labor would not support an increase to the GST, which "inflicts the heaviest punishment on those least able to afford it".

"Jacking up the GST to 15 per cent is not innovative, agile or creative," he said.

"This government's fixation with increasing the GST shows that when all you've got is a hammer, every problem looks like a nail."

His speech comes one day after Prime Minister Malcolm Turnbull's address to the conference, where he promised to focus on fairness.