40% of Irish primary schools are running a deficit just to provide heating and other essential services.
The Irish Primary Principals Network says the survey shows the urgent need for an increase in the capitation grant they get from the Department of Education.
It is used to cover phone, heat and insurance costs.
David Ruddy, President of the IPPN, says parents are usually the ones to take up the slack.
He said: "Voluntary contributions are probably the easiest, least disruptive way (to fund raise), so parents are being asked to dip into their pockets to help pay to heat the schools and keep them running."