Former Liberal leader John Hewson has questioned the logic of getting rid of the deficit levy on high-income earners when the budget is in a much worse position than it was three years ago.
The temporary levy - a two percentage point increase imposed on the top marginal tax rate - was introduced in 2014 under former prime minister Tony Abbott when he described it as a 'budget emergency".
Back then the 2016/17 budget deficit was projected to be $10.6 billion.
However, last December's mid-year budget review put it at $36.5 billion.
"Now we have got an even bigger budget emergency and we want to get rid of it," Dr Hewson told Sky News.
Treasurer Scott Morrison has vowed to end the levy as legislated on June 30.
But Dr Hewson wonders what is going to be put in its place in the May 9 budget - other tax increases and/or expenditure cuts?
Mr Morrison has long said Australia does not have a revenue problem but a spending problem.
"It's a mantra, it's not reality," Dr Hewson says.
Mr Abbott will get his chance to give his view on how the budget process is proceeding when he appears on the Ray Hadley 2GB radio program on Monday
Mr Abbott will fill the Monday morning slot held by Mr Morrison for several years after Hadley and the treasurer fell out last week.
Last week saw what Dr Hewson called an "embarrassing free-for-all" between ministers arguing whether young people should be allowed to tap their superannuation to help build a home deposit.
Prime Minister Malcolm Turnbull believes it is a "thoroughly bad idea" but Mr Abbott says people should be able to spend their own money on housing now rather on retirement in 30 or 40 years' time.
Tackling housing affordability will be a key plank of the May budget.
