Labor and the coalition have unveiled policies costing billions of dollars to boost housing supply in the coming years while offering incentives for first homebuyers in the interim.
Voters have also been promised a one-off tax offset of up to $1200 under the coalition, while Labor has pledged instant tax deductions of $1000.
The measures would cost $10 billion and $2.4 billion respectively.
But AMP chief economist Shane Oliver said the big-spending policies were at odds with previous pledges from the major parties to maintain fiscal responsibility.
"It's all inconsistent with spending restraint or getting the budget back under control and it seems over-the-top this time around," he told AAP.
"Major parties should be resisting the temptation to spend more.
"If they are going to provide tax relief, it should be on a permanent, logical basis rather than arbitrary sugar hits."
The major announcements came at coalition and Labor campaign launches on Sunday, a week before pre-poll voting begins.
Touring a housing development in Adelaide on Monday, Prime Minister Anthony Albanese defended his plan to allow people to secure a mortgage with only a five per cent deposit with the government going guarantor.
He's also pledged 100,000 new homes solely for first homebuyers under a $10 billion plan if Labor is re-elected on May 3.
"These two policies will make a significant difference to increasing supply but also importantly, to getting first homebuyers and particularly young Australians into their first home," Mr Albanese said.
With housing a critical issue among voters, the coalition announced it would allow interest payments on the first $650,000 of a mortgage for new houses to be tax deductible for first homebuyers.
That could save the average first homebuyer $10,000 a year.
The plan has found few friends among economists, who say it would disproportionately benefit high-income earners, push up house prices by increasing demand, and blow a hole in the federal budget.
But Opposition Leader Peter Dutton remains adamant it will incentivise housing supply as builders would be confident they had a buyer at the end of construction.
It's on top of the coalition's $5 billion kitty to unlock hundreds of thousands of homes by providing critical infrastructure to quicken builds.
The deductions are the "missing pieces of the picture", Mr Dutton said in Brisbane, where the coalition is trying to win back seats from the Greens.
"To allow support for young people to get the finance in the first place so that the banks will lend them the money and importantly obviously to be able to service the loan, to make the repayments," he said.
Tori Gibson, who is in her 30s, said she didn't think she would ever be able to afford to buy her own home without an inheritance.
She said the coalition's offer of tax-deductible repayments would probably be the better long-term solution for first homebuyers, but neither proposal solved the underlying problem.
"Essentially, we need more houses, that's really what we need," she said.
Dr Oliver said the rollout of large campaign promises did not send a good message after the major parties pledged to work to bring the budget into better shape.
"I can see why they want to (implement big-spending policies) because they want to be elected," he said.
"It's almost as if the pandemic has unleashed out-of-control spending by both sides of policies and taken spending to record highs."
