Teacher unions say the Ministry of Education will have to make cuts in order to pay $63 million a year in superannuation contributions for teachers.
The Government is moving responsibility for the payments to the ministry next year - a move mirrored in all state sector agencies.
The Budget delivered earlier in May contained no extra funding for the change.
The Post Primary Teachers Association and the Educational Institute say the ministry will have to cut spending in other areas to make the payments.
They say that will reduce the Government's extra spending for the sector.
However, Education Minister Anne Tolley says no decisions have been made on next year's Budget.