The Teachers' Union of Ireland says chronic under-funding of education is putting huge pressure on both schools and parents.
Barnardos is calling on the government to cover the cost of school books, and to ban voluntary contributions.
Analysis by the charity shows basic costs to send a first year student to secondary school is €814 , and €722 for a fifth year pupil.
A survey shows two thirds of parents, of primary school children, are worried about back to school costs while three quarters of families with secondary school pupils are concerned.
TUI general secretary, Michael Gillespie, says there's been a lack of investment in education for too long:
"What we've seen over the last number of years has been chronic underfunding of education in Ireland, where unfortunately the Irish system depends on volunteers across the board. Parents have to put into their own pockets to buy books, which are very expensive. Inflation is going to hit a lot of these things because there's always knock on cost. So it's going to get more expensive."
