Nearly half the schools in the East of England are facing a deficit this year, a survey of head teachers has found.
The National Association of Head Teachers said 48% of its members in the region feared they might have to cut staff next year to balance the books.
Jody Gee, chair of union in Essex, said schools faced an average rise of £205,000 a year in fuel costs while the government was offering £45,000.
The government said it had increased spending on schools this year by £4bn.
Ms Gee told BBC Politics East that schools were grateful for the government’s financial assistance, but she said it was “a small drop in a very large ocean”.