Former treasurer Peter Costello thinks he'll be dead and buried by the time the federal government has paid off the nation's debt.
Mr Costello warned Australia wouldn't be in a position to pay back money owed until spending was under control.
"It took us 10 surplus budgets to pay off last time. You would be doing well to pay it off in 10 surplus budgets this time," Mr Costello told ABC TV's 7.30.
"I think the probabilities are we will never get back to where we were, you and I will die before that happens."
Spending needed to be cut by at least $18 billion a year, Australia's longest-serving treasurer warned, adding it needed to be capped at 24 per cent of gross domestic product.
Right now it's at about 25 per cent.
He pointed out there had been 10 years of deficits which translated to borrowing about $370 billion.
"That money doesn't go away. It's going to be there, we're going to be paying interest on it until somebody pays it back," Mr Costello said.
He warned Australia was more vulnerable to a global economic downturn, compared to 2008 when it was in the best position of all western countries with no debt and triple-A credit rating.
"We are more fragile, more exposed. We don't have the same strength," he said.
