Leaders of seven bodies representing all schools and the four main churches have written a letter warning of a crisis in education funding.
The unprecedented joint letter has been sent to the Northern Ireland secretary and the head of the civil service.
On Tuesday, the Education Authority (EA) said it could not make £110m in savings this year.
In the said under-investment in schools would affect "every child and young person".
The letter to Chris Heaton-Harris and Jayne Brady has been signed by the chief executive of the Council for Catholic Maintained Schools (CCMS) Gerry Murphy and Controlled Schools Support Council (CSSC) Mark Baker.
