Hundreds of schools are operating in the red and extras like outdoor education programmes, new library books and computers could be axed.
The Ministry of Education's annual report on schools for last year shows about 15 per cent have three-year operating deficits.
Six per cent also have very low working capital ratios so they are unlikely to have enough cash to cover immediate bills.
"I'm not surprised. It is expensive to run a school and we don't get enough money for it," said Principals' Federation president Denise Torrey.
"So ... schools have to prioritise. And after that, they turn to the community to raise the money - which only works if your community is able to afford it."