As rising costs in food and fuel and pay anomalies hit budgets, some heads say they will be forced to lay off staff. They want ministers to include these escalating costs in a new funding review
Many schools are expected to cut staff numbers as the tight funding round, rising costs and slowing global economy bite.
Heads are demanding that the Government reviews its three-year funding settlement, to factor in wage rises and higher costs.
Ministers require schools to reduce spending by 1 per cent per year, while costs such as heating and transport are rising. School leaders say the only way they can save that money is by reducing staffing costs, which comprise four-fifths of a typical school budget.
At its conference in Liverpool next week, members of the National Association of Head Teachers (NAHT) will ask the union's leadership to negotiate more flexible funding in response to the state of the global and national economy.
Mick Brookes, its general secretary, said schools were being asked to implement a huge agenda of policy reform - not least the new diplomas - and needed more funding to do so.
Funding for the diplomas is expected to leave some schools with shortfalls ranging from pound;20,000 to pound;200,000.
Teachers' pay will rise by 2.45 per cent in the autumn - already more than heads had anticipated. In yesterday's planned strike, the National Union of Teachers was demanding 4.1 per cent.
Support staff's wages increased by 2.475 per cent this month, and they are seeking a 6 per cent rise next year. Many schools are already forced to fund tens of thousands of pounds in back pay, after it emerged that support staff had been paid inequitably for years.
George Phipson, a funding consultant for the NAHT, said the worst affected schools were often primaries that had embraced the Government's workforce remodelling agenda by hiring teaching assistants instead of teachers.
"They will have the biggest bills for back pay," he said. "You ask most heads now, and they say teaching assistants' salaries have advanced so much that they are almost as expensive as teachers."
The Department for Children, Schools and Families (DCSF) is offering schools benchmarking and planning information, and one day of assistance from a consultant to go through their books to look for potential savings.
But Mr Phipson said it had funded only 4,000 consultancy days a year, for more than 24,000 schools: "A lot of heads have said to me, 'Frankly, just give me the cost of the consultant'.
"We can safely say that the vast majority of schools will have to look long and hard at their budget to find those efficiency savings.
"It's not the sort of money you're going to save by just changing gas suppliers. You will see schools making redundancies or not replacing staff. Either way, you will see fewer adults looking after the children."
Lindsey Wharmby, a funding consultant for the Association of School and College Leaders, said the funding settlement was not generous. "Undoubtedly" some schools would have to make redundancies, or cut the staffing budget in other ways, she said.
The DCSF dismissed talk of school staff cuts as "speculation". "Schools are guaranteed a minimum increase of 2.1 per cent per pupil in each year - the great majority will see larger increases," a spokesman said.
"But we have been very clear over the last year that, while it is not growing at the unprecedented rates of recent years, it is enough to continue to deliver our major reforms."
'THE PUPILS WILL BE WORST AFFECTED'
In the same week that Wold Newton School was declared "outstanding", teachers learned that their effort and commitment would be rewarded with redundancies.
Jane Bellamy, head of the 122-pupil primary near Bridlington in East Yorkshire, said: "Everyone had been working so hard, and I had to tell them I was going to have to lay some of them off.
"They were shocked. If you were a successful company, you wouldn't have to lay off staff, would you?"
Two of the six teachers will probably be affected as Mrs Bellamy battles against rising costs and a tight three-year funding deal.
At their staff meeting last term, she went through the numbers: heating oil had gone up from 19p to 51p a litre in two years; gas had gone up 40 per cent in the past year; the salary bill for teachers and support staff had risen by 5.3 per cent.
But ministers had provided a guaranteed minimum funding increase of only 2.1 per cent. Mrs Bellamy said redundancies were the only option.
"There are going to be people whose lives will be turned upside-down," she said. "Instinctively, I blamed myself. But I went through the numbers again and again, and there was no other way."
As a rural school, Wold Newton was particularly hard hit by transport costs, she said.
In the past, pupils have spent half-days at a sports college 10 miles away, using its PE facilities. Last year, Mrs Bellamy paid about pound;80 for a charter bus for the round-trip. This year, quotes have ranged from pound;175 to pound;310. The cost of the trips was now "prohibitive", she said, and they would have to be cancelled.
Even school dinners have been affected, as food costs rise. Lamb has gone up by pound;2 a kilogram in the past month, forcing Mrs Bellamy to take it off the menu.
Ultimately, it is the pupils who will be worst affected, Mrs Bellamy believes. "When times are tight, it is the children who miss out," she said.