The South Australian budget could take a $577 million hit over the next four years because of lower GST returns, Treasurer Rob Lucas has revealed.
The lower forecast for GST collections has been included in the federal government's mid-year budget review.
It puts in jeopardy SA's budget surpluses over the forward estimates, though Mr Lucas says the government is determined to keep the state's finances in the black.
"There's no question, forecast GST write-down makes our task of budget repair more difficult," he said.
"Based on current estimates, our upcoming budgets would face small deficits over the next few years instead of modest surpluses if we didn't take corrective action.
"If these estimates are confirmed in next year's federal budget, the government will take corrective action."
In his own mid-year review last week Mr Lucas forecast the SA budget to return a $48 million surplus in 2018/19, lower than expected because of a softer property market.
Surpluses over the coming years were also projected to be lower than outlined at the budget in September, coming in at $95 million in 2019/20, $96 million in 2020/21 and $189 million in 2021/2022.
The estimated lower GST returns would wipe them out and more.
But Mr Lucas said GST forecasts "tend to jump around".
He said SA treasury officials would work with their federal counterparts over the next to weeks to analyse the latest estimates.
