Almost one in three local authority maintained secondary schools were in a financial deficit in 2017-18, new research has revealed.
The report, from the Education Policy Institute, found some schools have very large deficits, with one in every 10 council-run school having a deficit of over 10% of their total income.
The number of special schools in the red has also nearly doubled since 2014, with an average deficit of nearly a quarter of a million pounds, the analysis found.
The proportion of primary schools in deficit is significantly lower than secondary schools, at 8% in 2017-18.
However, the research did also find that more than 34% of secondary schools have balances deemed as 'excessive' according to the Department for Education.
The report calls on the Government to consider whether higher per pupil funding is needed before the Spending Review and if more help or advice can be offered to those schools facing large deficits.
