SCHOOLS facing budget cuts have again been warned they must not overspend, provoking anger among principals.
The Department of Education said schools had "no authority" to go into the red.
The department's finance director Gary Fair had already written telling head teachers they could not plan for deficits.
Secretary of State James Brokenshire indicated that a Stormont budget he would impose would cut 2.5 per cent from the education pot - a loss of around £50 million.
Debts are already soaring with schools predicted to be £75m in the red in the next three years.
Unions have warned that the cuts will mean schools will find it impossible to maintain their high quality of education.
Principals in Belfast wrote to parents, education bodies and politicians warning they would not make any further cuts.
In a new letter sent this week, Mr Fair said the department faced major funding pressures in 2017/18 and was anticipating having to make spending reductions across a wide range of areas.
While every effort had been made to minimise any impact on budgets, he said, some other funding streams such as extended schools "will unfortunately be affected".
He added that schools must make difficult decisions required to allow them to live within their budgets as a matter of urgency.
"I would again stress that, while legislation provides delegated budgets for boards of governors to deploy resources to best effect in delivering the highest possible quality of education for children, it gives no authority to boards of governors to exceed the limits of the budget delegated to them," Mr Fair wrote.
"Put simply, boards of governors cannot spend more than they receive without the express and advance approval of the Education Authority and they must not plan to do so."
Kathleen O'Hare, principal of Hazelwood Integrated College in Belfast, said cuts to extended schools and other streams represented a 2.5 per cent reduction.
"We have had no notice of this and have already planned and staffed next year with a full-time extended schools coordinator who has been employed with us since the beginning of this initiative," she said.
"It is too late for Hazelwood to invoke redundancy measures but I have had to notify her of the intention of DE to effectively remove her salary. I am deeply disturbed that DE have sent this at the end of June. I am also acutely aware that this giving with one hand whilst taking away with another will cut funding more from non-selective schools than grammar.
"I fully understand that we are living in times of acute financial constraints but we cannot be expected to contravene both employment practices or stand by whilst the most disadvantaged children in our school community are further affected."
