But the prime minister remains tight-lipped on when Australians will be able to burst the international border.

Mr Morrison has been to every state and territory except Tasmania over the past six weeks, with his planned visit to the Apple Isle cruelled by a last-minute lockdown.

Returning to federal parliament on Tuesday, he said the conversations among locals at pubs and clubs were vastly different to the chattering political class, likening his experience to a classic Jim Carrey comedy.

"It was a bit like The Truman Show when he gets to the edge of the bubble and finds out there's something else out there," Mr Morrison told coalition colleagues in Canberra.

"What Australians are living out in the rest of the country is what we have to protect, what we have to nurture, what we have to embrace and what we have to defend."

The prime minister said Australia was living like very few countries in the world - and it was not by accident.

"It's a product of the great will and determination, and strength and resilience, of the Australian people first and foremost, and the actions of our government working in concert with other governments around the country."

Hours out from the federal budget, he acknowledged the government had made some decisions that jarred with its conservative stripes, but argued the decisions were necessary responses to the health and economic crises.

One unanswered question causing massive consternation is when Australia's borders will reopen.

The budget will include an underlying assumption the borders will not reopen until some stage in 2022.

But a more precise timeline remains a mystery.

Treasurer Josh Frydenberg, who wore a tie decorated with tiny aeroplanes to parliament on budget day, remains coy on the reopening date.

He is also refusing to say how crucial the speed of the national vaccine rollout will be.

"It's very hard to be precise in the middle of a pandemic," he told reporters in Canberra.

"There's a lot of uncertainty globally, domestically, with respect to the virus.

"The key point is we will always follow the medical advice and we'll always do our best to keep Australians safe."

Opposition Leader Anthony Albanese said tourism operators and universities reliant on international students deserved clear answers on border closures.

"This government gives different answers every day and that is creating massive uncertainty for the tourism sector, for those who are reliant on our economy opening up," he said.

Mr Albanese said the federal government had two jobs - vaccinations and quarantine - and had fundamentally failed both tasks.

"Unless we get that right then you will have the continued and ongoing restrictions on our economy, you will have continued breakouts," he said.

Health authorities spread across two states are scrambling to respond to a surprise infection in a man who returned home from overseas.

Victorian authorities have confirmed the new local case of coronavirus after more than two months of no community transmissions.

But curiously, the man in his 30s had already quarantined in South Australia for two weeks after returning from overseas.

He returned home to Wollert north of Melbourne last week before developing symptoms on Saturday.

Health authorities are trying to determine the source of infection while contact tracers review his movements.

Australian Associated Press