A former headteacher has called for an investigation into a Kirklees special school he used to run.
The bill has skyrocketed from £209,423 in 2013/14 to £562,722 in 2014/15.
It amounts to more than double the bill for all the other Kirklees special schools combined and represents £4,736 per pupil per year.
Nick Hughes, of Fixby , claims the problem is caused by experienced teachers and support staff leaving the school or being absent on long term stress-related sick leave.
He says that problems began when the long-time headteacher retired and there was a change of leadership in September 2013.
Mr Hughes, 68, was headteacher at Fairfield from 1984 until the end of 2000. He has visited the school every year since, until last year, and kept in touch with several of the teachers.
He said: “Running a special school is a hugely complex job, but the situation at Fairfield School needs to be investigated.
“What has caused so many teachers and support staff to leave or be absent with work-related stress?
“This is a matter of public interest, as it has without doubt contributed to the supply teaching costs.
“Some highly qualified, talented and experienced people, whom I hold in the highest regard, worked at that school and, had the situation been different, they would still be there.
“Teachers who are skilled in the education of children with severe and profound learning difficulties are extremely thin on the ground. They are not sitting around waiting for a headteacher to ring them.
“I would be extremely surprised if the pool of supply teachers had anywhere near the expertise of the staff they are replacing.
“Continuity is particularly important for children with special needs. Experienced staff build very close relationships with the children and their families.
“This is a tragedy for these very vulnerable children.
“These children are hugely expensive to educate and it is quite right that society supports them in every way it can.
“But these huge supply costs in addition to the normal costs are a misuse of public funds which needs looking into.”
“Fairfield School caters for children aged three to 18. It is part of The Spenborough Co-operative Trust and comes under Kirklees Council ’s control.
It was last inspected by Ofsted in March 2013, when it was rated as Good with Outstanding features.
According to Kirklees, 26 staff have left from a total staff team of 122 since August 2013. A spokesman said: “This equates to 10.6% per year and is line with staff turnover across all Kirklees special schools.
“It is correct that two former assistant heads have retired since the last ( Ofsted ) inspection in 2013.
“Three teachers and five teaching assistants are currently absent from work due to illness.
“The figure of £587,250 relates to a period when a full review of all staff was taking place. This was designed to ensure the school had the best possible teams in place for the care and education of pupils.
“The school did not fill any vacancies with permanent staff during this review period but instead recruited supply staff. “The figure needs to be offset against insurance and also against the saving that was made by not recruiting permanent staff during the review.
“The staffing review is now complete and it’s expected that the school’s supply costs in 2015/16 will fall to a level which is in line with other special schools.
“When supply staff are taken on, proper vetting processes are in place and there are clear expectations that all have had essential training.
“The school now benefits from secure leadership which is contributing to high standards in care and education.”