The basic funding that schools get in Northern Ireland has been cut following the Stormont budget.
But they are getting some extra money to help with existing staff salary agreements and rising energy costs.
In a letter to schools, the Department of Education (DE) said it "has had to make some very difficult decisions".
The Education Authority (EA) may also need to find about £100m in savings from its block grant in 2022-23, BBC News NI understands.
That could affect services like Special Educational Needs (SEN), school transport, school meals or maintenance.
In delivering a budget for Northern Ireland in November, the Secretary of State Chris Heaton-Harris warned DE that it needed to make significant cuts to its "current spending trajectory".
