According to data collated by the National Union of Teachers (NUT) and the Association of Teachers & Lecturers (ATL), Buckinghamshire schools face a funding cut worth nearly £20 million.
This would mean £232 less is spent for every pupil at a state school over the year.
The figures relate to a proposed new funding formula which have been put forward by the government.
The NUT and ATL claim that 98 per cent of schools across the UK will lose out under the changes, leaving them with increased class sizes, loss of school staff, and cuts to extra-curricular activities and resources. The budget changes mean that Buckinghamshire would be £16.5m worse off in funding than they were in 2015/16.
The total estimated reduction across all schools in Buckinghamshire in real terms by 2020, under current Government policies. These include plans to reallocate school budgets according to a new national funding formula, and not increasing funding per pupil in line with inflation.
A statement from the NUT said: “Despite reassurances in the Conservative party election manifesto that school budgets would be protected, this is clearly not the case.
“The NFF [National Funding Formula] will simply redistribute existing money across the country, while the Government’s funding freeze and inflation and employer cost increases will cut the value of every school’s funding by almost 10 per cent.
“The National Audit Office has warned that schools will need to save £3 billion by the end of this Parliament and that they are ill equipped to do this.
“The latest DfE figures show that 60 per cent of secondary schools are already in deficit.”
NUT Divisional Secretary Annette Pryce said: “Under this Government’s funding policies, there are no winners, only losers.
“Buckinghamshire schools are being forced to make decisions that no head teacher should have to make.”
Andria Hanham, head of Mandeville School, said: “These projected figures are alarming, given the current pressures on schools as it is, especially in a ‘squeezed’ county like Buckinghamshire.
“Aside from stripping resources and materials away from students’ learning, these figures will have a further negative impact on the recruitment of teachers – which is already a huge issue.
“More children will need to be educated in Bucks in the upcoming years, with less and less teachers coming into the profession.”
Zahir Mohammed, Cabinet Member for Education and Skills at Buckinghamshire County Council, said: “As part of the Schools National Funding Formula we will be receiving an additional £10 million per year. That’s a great positive, providing the consultation is implemented. I haven’t seen these figures, so I can only tell you what I know.
“Buckinghamshire in the past few years has been one of the lowest funded counties in the country. We have been applying for funding that will bring us up to the national levels, to ensure we are equally funded.”