Companies such as airlines will be forced to reveal the full price of pre-selected extra costs, like luggage, movies or meals, in their initial advertised prices, under changes to law brought to parliament.
A review of the Australian Consumer Law found the payment process was potentially misleading and could result in consumers shelling out more than they intended if they didn't opt out before paying.
"This amendment ensures consumers are made aware from the start of the online payment process of the total possible amount they would pay if they do not opt out of pre-selected options," government minister David Littleproud said, introducing the bill on Wednesday.
The changes also adopt a report recommendation for evidence requirements to be eased, so that private litigants can rely on admissions-of-fact made in past proceedings.
Unconscionable conduct protections are also being extended to include publicly-listed companies, which were previously considered able to protect themselves.
"However, public listing is not necessarily a reflection of a trader's size, level of resourcing or ability to withstand unconscionable conduct," Mr Littleproud said.