One in six autistic pupils have not been to school at all since the start of this academic year, according to a new survey which found that mental health issues were often behind high levels of school absence.

Nearly half (45%) of the parents and children who responded to the UK-wide survey by the Ambitious About Autism charity said they felt “blamed” by the government for the absences.

Of those who missed school, 62% said it was due to mental health issues and 30% said they were too physically unwell to go to school. A fifth said their school place was not suitable.

The poll of nearly 1,000 autistic young people and their families comes as the government prepares to publish long-awaited plans to overhaul the special educational needs and disabilities (Send) system in England.

The government is expected to introduce measures it claims are aimed at boosting provision in mainstream schools so they are better able to meet the needs of children with Send, though it accepts some pupils will always require a specialist place.

About 70% of autistic pupils are educated in mainstream schools, but absence rates are high due to anxiety, sensory overload and inadequate support. Parents are concerned that new investment will not be adequate and the environment will continue to be unsuitable for many pupils.

Analysis of survey responses by Ambitious About Autism found that 16.2% of those who responded had not been in school at all since September. A third (32.8%) had missed one to five days, 11.3% missed six to 10 days, 12.2% had missed between 11 and 20 days and 7.4% had missed between 20 and 40 days.

Jolanta Lasota, the chief executive of Ambitious About Autism, said: “We cannot allow another generation of young people to miss out on opportunities to learn, thrive and achieve. We must ensure mainstream schools have the knowledge and confidence to support autistic pupils and these young people remain able to access specialist support when they need it.”

The most recent national figures published by the Department for Education showed that autistic children had far higher rates of absence than children and young people without special needs.

In the 2024-25 school year in England, those with autism spectrum disorder missed nearly 11% of sessions in mainstream and special schools, and more than 28% were classed as persistently absent by the Department for Education. In contrast, only 14% of children without special needs were persistently absent.

The figures also show that 5.5% of autistic pupils missed 50% or more of their time in school, five times more than those without special needs.

Among the absentees is Sarah Greaves’s autistic son Sam, 13, who is now being educated at home after his transition to secondary school left him with “autistic burnout”.

“He no longer wanted to be here, let alone go to school,” said Greaves. “The old Sam is now completely gone; he rarely leaves the house. If I wasn’t self-employed, I would have had to quit my job to support him.

“What Sam needed at school would make life better for everybody. He needed less focus on strict rules for minor issues which trigger anxiety in autistic young people and less focus on rigid school uniform policies which trigger sensory needs.”

On the government’s overhaul, Greaves said: “Everyone’s terrified that education health and care plans [which legally guarantee additional support tailored to an individual child’s needs] are going to be taken away.” She said her message to the government was: “Don’t take away our legal backstops.”

Erin, 20, from Hertfordshire, is still in her final year of schooling, studying for a BTEC after missing so much of her education. She told the Guardian: “School was really tough for me, and I missed out on a lot of it. It wasn’t that I didn’t want to be in school, it’s that I couldn’t.

“My autism was undiagnosed and I struggled with exhaustion, burnout, and what I now know was autistic meltdowns. Things got so bad that I ended up having psychiatric treatment and was held back by two years.

“I hope the government’s reforms will create a culture change in mainstream schools that makes them more accessible to autistic pupils. There is so much rigidity in the current school system that makes things really challenging.”

A Department for Education spokesperson said: “We are laying the groundwork for an inclusive education system where children are supported at the earliest stage and can thrive in schools that meet their individual needs, close to home.

“Our reforms will end the postcode lottery of support and tackle the barriers that keep children with Send out of school. We are already making this happen by expanding access to mental health support teams, investing £200m to train all teachers in Send and committing at least £3bn to create 50,000 new specialist places.”