The South Australian government is being urged to lobby for an extension to the federal HomeBuilder scheme amid warnings some SA applicants will miss out on the $25,000 grant through no fault of their own.
The state opposition says a shortage of building supplies and labour has caused significant delays for some new and off-the-plan homes.
It says that could mean people who met all the requirements for the grants when they signed contracts could be denied the cash if they can't provide a certificate of title by the April 30 deadline.
Opposition leader David Speirs said those affected just wanted to be treated fairly.
"The opposition has been inundated with heartbroken first homebuyers devastated they're going to lose this grant because of building delays that are completely out of their control," he said.
"For many South Australians, these grants were what made the dream of home ownership possible and they never imagined it could be ripped away from them like this."
The opposition said more than 1000 people could fall short at the April 30 deadline, although state Treasurer Stephen Mullighan said the government's advice was the figure would be less than 600.
But the treasurer ruled out intervening with the federal government because of an "equity issue".
"With every incentive scheme, there are requirements. There are thresholds that need to be met," he told reporters on Tuesday.
"The reason why we haven't asked for the scheme to be opened back up for this cohort of people after the scheme's been closed for nearly two years is because of that argument that it would be inequitable to all those other thousands of Australians who missed out over the past three years."
Opposition treasury spokesman Matt Cowdrey said the treasurer was acting as if the affected homebuyers were seeking preferential treatment.
"This is not a matter of applicants not having their paperwork in order. Far from it," he said.
"These are people who have been patiently waiting for their properties to be completed and factors outside their control could see them missing out on up to $25,000 towards their new home."
