The NSW government allocated a total of $13.8 billion for government schools and $1.2 billion for non-government schools in the latest budget. NSW government schools also received total federal government funding of $2.2 billion in 2017, Department of Education and Training figures provided to the Australian Education Union show. Non-government schools in NSW, including independent and Catholic schools, received a total of $3.3 billion from the federal government in 2017. Scots College, which recently submitted plans to the NSW government for a $25 million redesign of its library to look like a Scottish castle, received $7 million in government funding in 2016, on top of its income of $59.4 million from fees, contributions and other private sources. The 23 private schools, which also include SCEGGS Darlinghurst, Cranbrook and Loreto Normanhurst, had a combined capital expenditure of $141.9 million in 2016.

"These figures show how unfair public funding is fuelling the educational equivalent of an arms race," president of the AEU Correna Haythorpe said. "And when you can't even address the maintenance backlog at public schools, you're leaving them at a significant disadvantage, especially when you walk down the road to see these extravagant facilities." There is a maintenance backlog of $570 million at NSW public schools, according to the latest government audit. In total, government schools in NSW, which educate about 788,891 students, received $20,281 per student in taxpayer funds in 2017, while the state's non-government school network of 418,383 pupils received $10,755 per student.

"On average, government schools get higher funding than non-government schools but they also have higher need," Pete Goss of the Grattan Institute said. Mr Goss said fairness in funding was better assessed by looking at the Schooling Resource Standard (SRS), the Gonski Review's needs-based formula for measuring how much government funding each school was entitled to. "Virtually all government schools get about 87 per cent of their SRS," Mr Goss said. "Catholic schools typically are funded in the 90 to 95 per cent range and independent schools are all over the map. "Some independent schools are some of the most over-funded schools but some are the most underfunded and get only about 50 per cent of what the target is."

Federal government figures released in 2014 revealed all government and Catholic schools in NSW were funded at less than 95 per cent of their SRS, while only 64.8 per cent of NSW private schools were funded below that benchmark. Loreto Kirribilli, which is one of the most over-funded schools in the country, received 278.47 per cent of its SRS in 2016, which was equal to $6.5 million in federal government funding and $2.6 million in state government funding. The school, which has 80 per cent of students that fall into the top quarter in terms of socio-educational advantage, also had an income of $20.9 million from fees, contributions and private sources in 2016. Mr Goss said funding schools to their full SRS was important for getting the best educational outcomes. "Government school systems are obliged to take every student who comes to them and there's real merit to having a universal, free, good quality education system," Mr Goss said.