How do waiting lists impact therapy start times for autism? 

Long waiting lists for an autism assessment have become one of the most significant barriers to timely support in the UK. According to the National Autistic Society, over 227,000 people were waiting for an autism assessment in late 2025, with around nine in ten waiting longer than the 13-week maximum recommended in NICE guidance. Many families now wait more than a year for a child’s assessment, and adults frequently face waits of two years or more. These delays have a direct impact on when therapy starts, how support is coordinated, and how families cope during prolonged periods without help. 

NICE expectations versus real-world delays 

NICE guidance for children (CG170) and adults (CG142) states that diagnostic assessments should begin within three months of referral, led by a multidisciplinary autism team. However, NHS England’s national autism assessment framework acknowledges that most areas cannot meet this benchmark. Data highlighted by the National Autistic Society and independent analysis from the Nuffield Trust show a consistent rise in open referrals and rapidly expanding backlogs. In some regions, NHS trusts report average waits of around two years for adults, far beyond clinical standards. 

These long waits mean that families are left without clarity about a diagnosis, and without the structured support NICE expects to follow an assessment. 

How delays affect access to therapy 

Diagnosis is often the gateway to therapy in the NHS England. According to the National Autistic Society, delays in assessment “delay support and leave autistic people and their families in crisis.” This is because many services such as speech and language therapy, occupational therapy, psychology or post-diagnostic education programmes are only accessed after diagnosis or through autism-specific pathways. 

The Children’s Commissioner has reported that children frequently wait not only for assessment but then face further waits for therapy afterwards. Bottlenecks exist across SLT, OT, CAMHS and parent programmes, with each having its own queue. In practice, this means that even when a diagnosis is finally confirmed, therapy may still be months away. 

For autistic adults, NHS England’s mental health guidance stresses that people should not be excluded from psychological therapies while waiting for an assessment. Yet many adults report being told that services cannot proceed until diagnostic clarity is established, leading to prolonged gaps in mental-health support. 

Impact on children, adults and families 

Evidence from the National Autistic Society, Children’s Commissioner, National Audit Office and Autistica consistently shows that long waits increase stress, worsen mental health and contribute to behavioural escalation. Children waiting for assessment or therapy may struggle more in school, face higher risks of exclusion, and encounter delays in obtaining reasonable adjustments. Families often reduce working hours or leave employment entirely while managing needs without professional support. 

The National Audit Office also highlights a postcode lottery: some areas have far longer waits than others, creating unequal access to therapy and contributing to widening educational and health inequalities. 

Why waiting lists delay therapy start times 

Across the UK, long waiting lists affect therapy by: 

• Delaying the diagnosis required to access NHS autism pathways 

• Creating secondary queues for SLT, OT, psychology and post-diagnostic programmes 

• Increasing need complexity, meaning therapy may have to be more intensive once it begins 

• Heightening family stress, which can affect engagement with support 

• Reinforcing inequalities, as families who cannot afford private therapy wait the longest 

Key takeaway 

Long assessment waiting lists significantly delay therapy start times for autistic children, young people and adults across the UK. While NICE recommends assessment within three months, many people now wait a year or more. These delays postpone access to SLT, OT, psychology, and parent programmes, placing families under considerable pressure. This article provides general information only and is not a substitute for personalised clinical advice.