Thousands of children in England with special educational needs are waiting too long for an education, health and care plan (EHC), the BBC has learned.
The EHC plans set out a child's needs and the support to which they are entitled.
Once a plan is requested, the law says councils should normally finalise them within 20 weeks.
But through Freedom of Information requests, the BBC has learned around four in 10 plans have taken longer.
The BBC asked 152 councils in England about the time it took to issue EHC plans.
Sixty-five councils provided comparable data for the last four academic years, starting in 2014-15.
Over that period, 26,505 applications took longer than 20 weeks to finalise - including more than 6,000 last year alone.
Longest individual waits for a finalised EHC plan:
- Suffolk: 1,023 days
- Tower Hamlets: 1,014 days
- Isle of Wight: 1,005 days
- West Sussex: 973 days
- Liverpool: 945 days
- Dorset: 924 days
- Haringey: 915 days
- Havering: 898 days
- Southend-on-Sea: 871 days
- Worcestershire: 870 days
Source: BBC Research
The longest wait for an individual application was in Suffolk - where it took the council 1,023 days, or nearly three years, to finalise one EHCP application.
Suffolk County Council said an increased demand for EHCPs had proved particularly challenging - happening at the same time as the transfer from the old system of Statements of Special Educational Needs (SEND).
Councillor Gordon Jones, the council's cabinet member for education and skills, said: "Our priority is to ensure every child gets the correct help and support they need to prosper and develop.
"The increase in demand for education, health and care needs assessments for children and young people in Suffolk is a matter that I am taking very seriously.
"The development of our SEND strategy is driving improvement across SEND and all agencies involved in Suffolk."
Fifty-two councils told us that they had taken more than a year to finalise an EHC plan for at least one child.
While thousands of families are still waiting longer than 20 weeks for a finalised plan, the data suggests the mean and median waiting times are improving at many councils.
The number of requests for EHC plans has soared in recent years.
Sixty-one councils provided data on how many applications they had been receiving.
Between them, they were sent 16,696 requests for a needs assessment in 2014-15, but 28,507 in 2017-18 - a 70% increase.
West Sussex County Council told the BBC it had seen a 44% increase in the number of EHC plans it holds over the last four years.
A council spokesman said: "Despite this increase, there has been a year-on-year improvement in us meeting the 20-week deadline for finalising EHCPs and we are committed to continuing this."
East Sussex County Council told the BBC it had not been given the resources to match.
"The national funding formula has not kept up with the increase in costs councils face as a result of more requests for EHCPs and specialist placements," the council said.
Challenged at tribunal
The number of parents taking councils to tribunal to challenge them at various stages of the EHCP process nearly doubled over the four years - up from 1,041 in 2014/15, compared with 1,988 in 2017/18.
Fifty-eight councils provided comparable data on these appeals.
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Judith from Hastings appealed when East Sussex County Council decided not to assess the needs of her daughter, Hope, who has autism.
"I submitted papers to a tribunal, by myself, I didn't get any legal help. At that level it's a paper tribunal, so you're not 'in court' as such. But you still have to get your words in right.
"Very very stressful, lots of research on the internet. For three weeks I spent a couple of hours a night on it."
In the end, the council conceded to Judith before a tribunal.
"I remember sitting in the car literally in tears, feeling so relieved, but scared, because somebody was coming in to assess my child and that still didn't guarantee that what they saw would guarantee her an EHCP."
The BBC found that councils concede roughly four in every 10 appeals before tribunal.
'Needs more resourcing'
Huw Merriman, MP for Bexhill and Battle, co-chaired a parliamentary group on autism. He praised the "brilliant" research - and said it "requires a justification".
"I don't think local education authorities understand how plans work, I don't think they understand their duties, and I think it needs more resourcing."
Nadhim Zahawi, Minister for Children and Families, said: "Our ambition for children with special educational needs and disabilities is exactly the same for every other child.
"We are pleased to see that local authorities are improving the speed at which they are assessing SEND children.
"Where a local authority is performing significantly below the national average, we have been working with them through our specialist team of SEN advisers to improve performance."