Catholic schools in NSW receive $300 million in taxpayer funding every six months but face far less scrutiny from the state government over outcomes and performance than public schools, prompting calls for greater transparency.

While NSW Treasury officials pored over NSW Department of Education (DOE) budgets this year, the NSW government's only budgetary oversight of the Catholic sector's annual funding was a one-page document stating how much money it would be paid.

Former NSW Education Minister Adrian Piccoli said the document, obtained by Greens MP David Shoebridge under freedom of information, showed that schools receiving large amounts of public money were not subject to enough scrutiny.

"They get more public money than quite a few government agencies," Mr Piccoli said. "I'm not suggesting they are doing anything wrong. But the public has a right to know what's happening inside the schools that are getting that money."

Catholic Schools NSW said the document was a payment notice, not an accountability document, and did not reflect its reporting requirements to the state government, which were set out elsewhere, such as the education act and regulations set out by the NSW Education Standards Authority.