People will get only about half of the claimed $550 fall in prices from the abolition of the carbon tax, the nation's competition watchdog believes.
Australian Competition and Consumer Commission chairman Rod Sims said though the $550 fall - often quoted by Tony Abbott - was a reasonable number, about half of it would not be directly evident to consumers.
And he has put big names in the airline and construction industries on notice that their claims about the carbon tax has to be matched by evidence.
The ACCC has been given the job of policing the repeal of the carbon tax. It believes some consumers, particularly electricity and gas users, may get a small carbon tax rebate in the mail from their power suppliers. People will then notice lower charges in their quarterly bills.
The commission has a list of about 100 companies and 20 councils that it says indicated they were pushing up prices because of the carbon tax.
Mr Sims said the commission would be "knocking on doors" to ensure consumers benefited from the repeal of the tax.
"We've got no doubt it will happen and the Prime Minister's $550, I think, is a pretty reasonable number," he told _The West Australian _.
"About half of it people are going to see, in their electricity and their gas bills, but the other half they won't see but it will be there."
While electricity and gas prices will fall, the ACCC cautions against people expecting huge drops. It found that retail electricity prices had risen significantly for at least five years, with the biggest impact coming from network upkeep costs.
Some companies have said that they will not reduce their prices because they absorbed the carbon tax. These include airlines Qantas and Virgin.
Mr Sims said for those firms claiming to have absorbed the carbon tax cost, the commission would be looking to find out what prices would be for goods if not for the tax.
"They made the claim that they had absorbed the increase but we've got to see the evidence," he said.
"I think we have every right to be sceptical about their claims."
The ACCC will maintain its focus on carbon price falls for the next year. It has powers to seek corrective action and fines against firms found to have misled consumers about the impact of the carbon tax.
The refrigerant gas sector, which was the source of many claims of gouging after the introduction of the carbon tax in 2012, will be examined closely.