Some of Australia's most elite high-fee private schools are receiving taxpayer funding almost three times greater than their entitlements while others schools remain grossly underfunded, official Education Department data reveals.
The finding bolsters Education Minister Simon Birmingham's claim that some schools are "over-funded" and may need to have their funding frozen under a new funding deal from 2018.
The federal Department of Education data shows more than 150 private schools across Australia received funding above their Schooling Resourcing Standard in 2014, Fairfax Media can reveal.
The Schooling Resourcing Standard (SRS) - the bedrock principle of the Gonski Review into school funding - measures how much government funding each school is entitled to, including extra loadings for disadvantage.
In NSW 73 private schools schools received more than 100 per cent of their SRS while every public school in the state was funded below the appropriate level.
Loreto Kirribilli, an elite Catholic girls school charging almost $19,000 a year in fees for senior students, received 283 per cent of its funding entitlement, making it the most "over-funded" school in the country.
Monte Sant' Angelo Mercy College, an exclusive all girls school in north Sydney, received 277 per cent of its SRS level while Saint Ignatius' College Riverview received 263 per cent. I
Other elite schools in NSW that are over-funded include Sydney Grammar School, Kincoppal-Rose Bay School and Kambala in Rose Bay.
The data shows all public and Catholic systemic schools in NSW and Victoria were under-funded, compared to 65 per cent of private schools in those states.
Over-funded schools include Melbourne Grammar School, which received 144 per cent of its SRS despite charging up to $30,360 a year in fees.
Christ Church Grammar School, a primary school in South Yarra that charges parents up to $26,005 a year, received 130 per cent of its SRS entitlement
Peter Goss, education program director at the Grattan Institute, said the over-funding revealed in the data reflected decades of complicated deals between governments and different school funding sectors.
The Gillard government's Gonski reforms, while offering more money to needy schools, had locked in the problem by guaranteeing no school would be worse off and offering private schools generous indexation rates.
"That went against all principles of needs-based funding and dramatically blew out the costs," Mr Goss said.
He said emergency action should be taken to stop the disparity between schools worsening.
"Every dollar that goes to a school funded above its SRS is a dollar that cannot go to a school that needs it more," he said.
"Under the current legislation it will take decades to return those schools that are significantly over-funded to the needs-based standard.
"At a minimum, schools that are over-funded should not get annual increases - their funding should be frozen."
Senator Birmingham said he would not buckle in the face of "scaremongering" from Labor about a schools "hit list" and that he was determined to end the inequalities between states and school sectors.
Independent Schools Council of Australia executive director Colette Colman said that hitting independent schools deemed to be over-funded would only save the Commonwealth government 0.5 per cent of its total spending on schools.
Many of the schools that are technically over-funded include low-fee schools and others specialising in students with disabilities, she said.
The data shows a great level of disparity between schools with some private schools funded well below their SRS entitlement.
Meanwhile, public schools in the ACT were funded at 115 per cent of their SRS and public schools in Western Australia at 99.7 per cent.
National Catholic Education Commission executive director Ross Fox said: "The number one priority must be to move schools and systems towards funding that reflects their needs, not to impose cuts or draw up a 'hit list'."
NSW: most over-funded private schools
Government funding to School Resourcing Standard: 283%
Annual fees (senior years): $18,675
Monte Sant' Angelo Mercy College
Government funding to School Resourcing Standard: 277%
Annual fees (senior years): $19,680
Saint Ignatius' College Riverview
Government funding to School Resourcing Standard: 263%
Annual fees (senior years): $25,680
Brigidine College, St Ives
Government funding to School Resourcing Standard: 197%
Annual fees $16,330
Northern Beaches Christian School, Terrey Hills
Government funding to school resourcing standard: 184%
Annual fees (senior years) $13,990
Victoria: most over-funded private schools
St Paul's College Kew, special school for students with disabilities
Government funding to School Resourcing Standard: 165%
Melbourne Grammar School
Government funding to School Resourcing Standard: 144%
Annual fees (senior years): $30,360
Al Siraat College
Government funding to School Resourcing Standard: 135%
Annual fees (senior years): $2,732
Christ Church Grammar School, South Yarra
Government funding to School Resourcing Standard: 130%
Annual fees (senior years) $26,005
Insight Education Centre for the Blind and Vision Impaired
Government funding to School Resourcing Standard: 126%
Annual fees: NA