Struggling parents claim they are cutting back on food and household bills to meet the costs of going back to school.
Children's charity Barnardos revealed mothers and fathers were frustrated at high prices, with some forking out 770 euro for a child's first year of secondary school.
And hard-pressed parents could have to spend up to 620 euro per child ever year after that, according the National Consumer Agency (NCA).
Fergus Finlay, chief executive at Barnardos, said parents were worried about how they were going to make sure their children had what they needed to get an education.
"Many parents are being forced to make very difficult choices and many are getting into debt to pay for uniforms, books and other education expenses," he said.
"Concrete solutions for tackling the costs associated with sending children to school are long overdue."
One parent told the charity: "We cut back on food and let other bills go unpaid to ensure children have what they need for school.
"We're living on the edge all the time. So much for free education."
Elsewhere, research for the NCA found parents expected to pay 487 euro per primary school child this September, and 620 euro each for secondary school.
Nearly six out of 10 would use their regular income to pay for school expenses, and 78% were more concerned about costs than last year, Ann Fitzgerald said. Some 15% of the 1,000 parents quizzed would dip into their savings, and 5% would be forced to pay with a credit card or overdraft money.