The federal government will end petrol excise relief, but insists motorists won't be hit too hard at the bowser.
Treasurer Jim Chalmers confirmed the government would stick with a September 28 deadline on the temporary fuel excise cut of 22 cents per litre, citing the need for "responsible budget management" amid other increasing pressures.
The Australian Competition and Consumer Commission would have a role to play in ensuring prices didn't rocket once the cut ends, he said, noting plenty of fuel had been purchased by distributors at a lower price and that should be passed on to drivers.
"We're under no illusions this will be difficult for people - it's a difficult decision for us to take as well," Dr Chalmers told reporters on Tuesday.
"But we put a premium on responsible budget management, we do have to make room for these pressures ... ending that fuel excise relief next Wednesday night is part of the story."
He pointed to lower fuel prices that in previous months as encouragement consumers wouldn't cop too much of a monetary hit.
"We need to remember that fuel prices in most parts of the country at the moment are now around 50 cents a litre below the peak recorded in July, and that's obviously a welcome development," Dr Chalmers said.
"Most people understand the budget can't afford to keep the excise cut going forever, and people are preparing for the fact that we'll return to its normal setting."
The government had been working closely with service stations and suppliers to understand there was 700 million litres of lower-excise fuel in the system, adding the consumer watchdog expected prices would not soar when the tax is reintroduced, he said.
"This is 700 million reasons why the price shouldn't shoot up ... on the night that the excise relief ends," Dr Chalmers said.
"The ACCC and the government expect the price of petrol shouldn't shoot up at the bowser on Wednesday night by the full (amount) if the normal market pressures are in operation."
