A network of school leaders in Worcestershire has expressed "grave concerns" about an "immediate funding crisis" caused by staff pay rises.
In a letter to MPs, the Worcestershire Association of Secondary Head Teachers said the 5% increase was "significantly higher" than budgeted for.
Schools faced a choice between cuts to staff or maintenance, the letter said.
The Department for Education said core funding had increased by £4bn this year.
The letter, written on behalf of 32 school leaders in the county, was signed by Bryn Thomas from Wolverley CE Secondary School.