A new report by education economist Adam Rorris shows NSW is over-funding private schools by $160 million, while public schools remain under-paid by almost half a billion dollars.

When state and federal money is combined, it showed St Mary Star of the Sea College had been over-funded $1,225,926 in 2018.

The report commissioned by the NSW Teachers Federation revealed the public school system this year received $470 million less from the NSW government than was needed to meet the state's share of the Schooling Resource Standard, the benchmark for adequate funding.

“This analysis highlights a combined NSW overspend in the non-government sector of $160 million in 2018 alone and a corresponding $470 million underspend for NSW public schools,” NSWTF president Maurie Mulheron said.

“Under the amended Australian Education Act, NSW is to provide 20 per cent of the Schooling Resource Standard to private schools. The evidence shows Minister [Rob] Stokes is justified in opposing the Morrison Government’s $4.6 billion special deal to private schools.”

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Catholic Schools NSW disagrees, and has taken aim at Member for Kiama, Gareth Ward for not supporting the new school funding arrangements.

CSNSW chief executive Dallas McInerney called on Mr Ward to persuade Mr Stokes to sign up to the deal which will see the Morrison government create a special $1.2 billion fund for private schools and pay it directly to Catholic and independent school authorities to distribute as they see fit.

The “choice and accessibility fund” is in addition to a separate $3.4 billion cash injection to help private schools adjust to a new model for determining socioeconomic disadvantage.

Mr McInerney said this funding was to be a welcome relief for low-fee Catholic school parents across NSW because it would ensure fees would remain affordable for the next decade.

“Instead, the families of students at St Paul’s Albion Park, Saints Peter & Paul Kiama and other local schools now end another term with their family budgets under a cloud, thanks to Mr Stokes’ decision,” he said.

Mr Ward, the parliamentary secretary for education, backed his minister’s stance.

“We are the Gonski state. The fundamental principals of Gonski mean we are needs-based and sector-blind,” he said.

“We absolutely support our catholic and independent schools but I don’t want to see a return to funding wars where we spend more time arguing about education funding than we do delivering it.”

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Meantime, Mr Mulheron said the study and recent media comment exposed the incessant greed of the non-government sector and highlighted the urgent need for the state government to bring the sector back to the legislated 20 per cent SRS share.

He commended Mr Stokes for remaining “steadfast in both his opposition to special deals as well as his commitment to bringing overfunded schools and systems back to what is their legislated share of public funding”.