Barnardos says the government needs to do more to help parents with back to school costs.
A survey by the charity found more than 60% of parents with primary school children are worried about back to school costs and the rising cost of living.
While three quarters of families with children in secondary school are anxious about the costs.
Barnardos wants to see free schoolbooks and an end to schools asking for voluntary contributions.
The charity's CEO Suzanne Connolly, says this year's increase in the back to school payment for uniforms and shoes is welcome, but it's still not enough:
"So that was really appreciated by parents and 24% of the parents in our survey do receive the back to school allowance. However 72% of those said it isn't enough and 76% of parents who participated in our survey did not receive that and they're really struggling to make ends meet. It costs over €400 to send a child to fourth class and over €800 to send a child to secondary school."
