Teaching union leaders have criticised Ofsted for not acknowledging that “totally inadequate funding levels” are undermining schools and support services for young people.
The inspectorate’s annual report published today warns that almost 500 schools have been rated as less than "good" for more than a decade.
Chief inspector Amanda Spielman has also raised concerns that provision for pupils with special educational needs was too disjointed and too inconsistent.
However, unions have urged Ofsted to recognise how a lack of funding is contributing to these issues.
Stephen Rollett, curriculum and inspections specialist at the Association of School and College Leaders, said: “Amanda Spielman is right to say that some young people have 'the deck stacked against them', but we wish she would acknowledge that the totally inadequate level of funding in schools and local support services is undermining efforts to improve their life chances.”
He also raised concerns about how cuts were affecting schools' ability to support SEND pupils.
“Schools are working tirelessly to provide the most vulnerable children in our society with the education they need and deserve in the face of significant budget cuts as well as the erosion of local services for families and children.
“These funding pressures make it more difficult to give children the individual support which is so important in helping them to overcome learning challenges.
"And it means that schools are less able to put in place the early intervention which prevents challenging behaviour escalating to the point of an exclusion. Schools are doing their very best for children with special educational needs but are being expected to do more with less,” he added.
Launching Ofsted’s annual report today, Ms Spielman highlighted that exclusions of pupils with special educational needs or disabilities were increasing.
She also said that the quality of education, health and care plans (EHCPs) for young people was too variable adding: “The result is, the gradient for some young people with SEND is getting steeper, not shallower.
During a questions session at the report launch, Mary Bousted, the joint general secretary of the NEU teaching union, asked Ofsted bosses whether they were sure that the issues facing pupils with SEND were not being caused by a shortage of funding.
Speaking to Tes afterwards, Sean Harford, Ofsted’s national director of education, said: “We just don’t know whether issues can be pinned down to funding.
“It's not that we are shying away from [talking about funding] because in further education we have been very clear and the report we produced says that. We are not worried about saying that sort of thing but we need the evidence to say it."
Ms Spielman had warned that “real-term cuts to FE funding were affecting the sustainability and quality of FE provision”, in a letter to the Public Accounts Committee just over a month ago.
The NAHT headteachers' union has also called on Ofsted to consider funding as part of its annual report.
Paul Whiteman said: “As has been widely acknowledged, schools are now expected to do far more than ever before. We've also seen that the services that schools have relied on in the past have been cut back or have disappeared. We also know that school budgets are at breaking point.
"That is not a sustainable situation to be in. Nobody is well served if we allow this situation to continue unchecked.
"Four-fifths of our members expect a deficit budget next year. The IFS has said that school budgets are eight per cent down. The NAO recognises that schools have to find £3bn of savings.
“There's plenty of evidence of a school funding crisis. Ofsted's annual report is incomplete without a verdict on whether schools are sufficiently funded for the work they are expected to do.”