One in three school leaders in England say they are having to cut back on teaching staff to save money, according to a new survey.
And seven in 10 say they have had to reduce the number of teaching assistants they employ, despite a steep rise in the number of children needing extra support in the classroom.
Schools are also having to cut back on IT spending, while the funding squeeze means they are having to limit the range of subjects they can offer to students.
Funding per student in England has only recently returned to 2010 levels in real terms, after a decade-long squeeze forced schools into a wave of cuts.
But the recent largesse comes as school leaders are also having to fund an above-inflation pay rise for teachers, a massive spike in energy costs and tackle the backlog of maintenance that built up during the austerity years.
And the cuts are having a particularly debilitating effect on low-income students, according to Sir Peter Lampl, chairman of the Sutton Trust, a charity which promotes social mobility and which commissioned the survey.
“The erosion of schools funding coupled with rising costs is having a major impact on the ability of schools to provide the support that low-income students need,” he said.
“It’s disgraceful that increasing numbers of school leaders are having to cut essential staff and essential co-curricular activities.”
Almost a third (32%) of senior leaders said financial pressures had forced their school to cut back on teaching staff, according to the survey of 1,282 school staff in England, carried out by the National Foundation for Educational Research.
Schools in North-East England — where education attainment is lower than in any other English region — were most likely to be cutting teaching staff.
And almost seven in 10 (69%) said their school had cut back on teaching assistants, at a time when almost a fifth (19%) more students require extra support in the classroom.
A half of senior leaders said their school had to cut back on IT equipment (51%) or trips and outings (50%), while sport and other extra-curricular activities have also been scaled back (27%).
But perhaps even more concerning is that more than a quarter of school leaders (29%) said they had been forced to reduce subject choices for students as a direct result of financial pressures.
This is likely to mean fewer options for design and technology courses, offering only one modern foreign language at examination level, and fewer arts courses, such as drama and dance.
“The government’s rhetoric on education being a priority is a sham,” Sir Peter said. “School funding is inadequate and has to be urgently reviewed.”
The survey also found that almost half (47%) of school leaders were using Pupil Premium — money allocated to support the most disadvantaged students — to plug holes in their budgets.
Education Secretary Gillian Keegan said school funding was at its highest-ever level in real terms per student and would rise faster than forecast inflation.
“With school funding set to be at its highest ever level next year, even accounting for inflation, parents everywhere can be confident schools are being supported to let teachers get on and do what they do best – teach,” she said.
But Pepe Di’Iasio, general secretary of the Association of School and College Leaders, said school leaders were having to make impossible decisions over where to make cuts.
“Reducing teaching assistants means less support for children with additional needs; reducing teachers means larger classes and cuts to the curriculum,” he said.
“The reality is that the government’s record is one of underfunding, complacency and neglect.”