A county council said it was calling on the government to "urgently reform" the "broken system" for children with special educational needs and disabilities (SEND).
Conservative-run Norfolk County Council said it – along with schools – was struggling to meet "unprecedented demand" and it was overspending its budget to cope.
The council’s Labour group said the call for change was "a little bit too late".
Education Secretary Bridget Phillipson said the system was "in need of long-term renewal".
She added that the government would "restore parents’ trust that their child will get the support they need".
Demand for provision for children with additional needs has increased significantly in recent years.
According to government figures, 18,994 children in schools in Norfolk required support for special educational needs in 2018/19.
That number had increased to 24,825 by 2023/24.
A report for the council’s cabinet said its ring-fenced schools’ budget, the Dedicated Schools Grant (DSG), is continuing to overspend – with its forecast cumulative deficit estimated to be £115m by March 2025.
The council’s deputy leader Andrew Jamieson said that whilst the council was investing £120m to create 2,000 more specialist school places, schools were struggling to cope.
"There is now national recognition that the education system for children with SEND is broken. It is not delivering the best outcomes for children and the current budget being set by the government is totally insufficient to meet the needs of our children."
Mr Jamieson said the council’s budget from the government was "totally insufficient” and the system needed "urgent reform".
He added that he had written to the new education secretary, Ms Phillipson.
Councillor Mike Smith-Clare, deputy leader of the Labour group, said the council should have called for action sooner.
"It’s a little bit too late that the cries of help are being said. Why weren’t those representations and those appeals for financial support being said in the previous (Conservative government) administration?"
"I’m just angry that it’s got to this state," he added.
Ms Phillipson said the government would take a "different approach" to SEND provision.
"We will restore parents’ trust that their child will get the support they need in mainstream school, if that is the right place for them. And that there will always be a place in special schools for children with the most complex needs," she said.
"We have a broken system in desperate need of long-term renewal. I won’t make false promises, change won’t feel as quick as parents – or I – would like. I will make sure our approach is fully planned and delivered in concert with parents, schools, councils, and everyone who works with children."
