More Victorian private schools are set to be stripped of their payroll tax exemption within the next five years.
In a new report, the Parliamentary Budget Office estimates another 18 Catholic and independent schools will join the current list of 60 to lose their longstanding exemption to payroll tax.
Melbourne schools expected to fall victim include Alphington Grammar School, De La Salle College in Malvern, Marcellin College in Bulleen and Fitzroy Community School.
Clarendon College in Ballarat, Ballarat Grammar in Wendouree, Goulburn Valley Grammar School in Shepparton and Girton Grammar School in Bendigo are the four regional operators in the firing line.
The independent agency predicts the schools will become liable to payroll tax by 2029 as their income per student will pass the $15,000 threshold.
The analysis, requested by opposition education spokeswoman Jess Wilson, suggested their addition will raise an extra $26.9 million in revenue for the state over that span.
The May state budget flagged about 110 non-government schools would lose their payroll tax exemption from July next year, in a move to bank $422.2 million over the forward estimates to help pay off the state's COVID-19 debt.
The list was whittled down the list to 60 after backlash from the sector, leaving a $100 million hole in the budget.
The Victorian government committed to assess private schools against the $15,000 threshold each year until at least the start of 2029, rejecting calls for it be indexed to annual inflation.
Treasurer Tim Pallas maintained locking in the threshold gave schools more certainty and played down the significance of more schools being captured by the tax.
"There will be more schools added as, over time, there is appreciation in the fees," he told reporters at state parliament on Wednesday.
"But that's a relatively modest increase out of the 667 (schools) who are not affected."
The Victorian opposition has expressed concern schools could pass on the cost of their payroll bill to parents and pledged to scrap the tax if elected in 2026.
"Labor's schools tax is an unfair and punitive tax on educational choice and opportunity," Ms Wilson said.
Victorian government schools are not exempt from payroll tax but no other state or territory takes payroll tax from non-government schools.
