The primary teachers' union has demanded a re-think of a plan that will allow only a quarter of schools be in with a chance of getting the additional book rental funding.
In October's Budget, Education Minister Ruairi Quinn announced the provision of an additional €15m for book rental schemes in primary schools.
However, schools that have any form of rental scheme in place will be excluded from applying for this money.
The Irish National Teachers' Organisation (INTO) said three-quarters of primary schools operated some form of a book rental scheme.
INTO general secretary Sheila Nunan said the decision to exclude schools was made on "very dodgy information: schools were asked if they had a book rental scheme and had to answer 'Yes or No'".
Ms Nunan said the department made no effort to find out details of the rental scheme in individual schools.
She said it didn't ask "was it one book or all books?".
These schools had fundraised to make up for inadequate state funding for school books. They had tried to improve the situation for hard-pressed parents, she said.
"It's nothing more than a slap in the face to schools. The minister's commendation of their efforts without any money will sap any remaining goodwill," said Ms Nunan.
She asked why should schools make the effort to make up for inadequate funding if their only reward was to be commended and excluded, adding that the proposal was completely unacceptable.
"Most schools could expand book rental schemes if they got additional funding but the minister is refusing to reconsider.
"Penalising schools that have struggled and made sacrifices to support book rental schemes is wrong," she said.