GST hikes remain an option: Turnbull

Prime Minister Malcolm Turnbull insists GST hikes remain on the table but that shouldn't be an excuse for the states not to find efficiencies in spending.

Mr Turnbull says states need to work to improve services and can't treat the commonwealth government as an ATM.

"You can spend a lot of money on something and make no difference at all ... go backwards," he told Adelaide's FIVEAA radio on Wednesday.

He says he wants to change the way politicians speak from slogans about how much money is being spent to "businesslike" talk about what outcomes that will be achieved.

Opposition Leader Bill Shorten believes the government has an "undeclared plan" to put a GST on everything and increase the rate.

"I think Malcolm Turnbull and the Liberal Party need to focus on the unfairness in our tax system rather than slugging millions of people with new and extra taxes," he told reporters in Sydney.

He described the Liberal plan on GST as a "magic pudding".

Any increase in GST revenue has to go to the states, but Mr Shorten said it is also being flagged as a remedy to the shortfall in funding in schools and hospitals, and at the same time providing income tax cuts and help balance the budget deficit.