Teacher aide hours and numbers are being cut by schools because of the minimum wage hike.
Schools haven't been given an increase in funding to meet the wage raise, meaning they're struggling to pay.
Post Primary School Teachers Association President, Jack Boyle, told Mike Hosking some schools have already had to cut staff.
He says teacher aides are vital and schools would be at a huge loss without them.
"Unfortunately principals have to make pretty unfortunate calls, pretty negative calls for sustaining those workers who do such fabulous work in schools, often working with out most vulnerable students."
Boyle says teacher aides are currently paid out of schools' operations grant with limited money.
He says the government promised more teacher aide funding but that hasn't happened yet.
"There may be moves to centralise funding so that means that you'd no longer have the arbitrary cap based on the operations grant and you'd probably to then have permanence for these workers and the critical work they do."