What Timelines Are Involved in the Evaluation Process for Autism? 

The process and waiting times for an autism evaluation in the UK can vary widely, but clear standards are set by the NHS and NICE. According to the NICE guidance on autism in under-19s (CG170) and autism in adults (CG128), assessments should begin within 13 weeks of referral. In practice, however, most people wait considerably longer. 

1. From Referral to Assessment 

Once concerns are raised, by a GP, teacher, or health visitor, a referral is made to a specialist autism assessment team. NICE guidance recommends this should happen promptly, especially in younger children, as early identification improves outcomes. The NHS England framework for autism pathways (2023) advises integrated care boards to ensure assessments start without unnecessary delay. 

2. Current Waiting Times in the UK 

Despite these standards, recent data show growing delays. The National Autistic Society (2025) reported that more than 236,000 people in England were waiting for an autism assessment, and nearly nine in ten had waited longer than the recommended 13 weeks. 
Similarly, an N8 Research Partnership report (2025) found average wait exceeds a year in some areas, with significant regional variation. These findings echo NHS data cited by the Royal College of Psychiatrists (2023), showing adult assessments often taking ten months or more. 

3. Diagnostic Evaluation 

Once started, the assessment process itself typically takes four to eight weeks, depending on the complexity. It includes developmental history, structured observation tools (such as ADOS or ADI-R), and input from families or educators. 
Private clinics, such as Autism Detect, may offer autism assessments aligned with NICE guidance and conducted by qualified clinicians, sometimes with shorter waiting times, but should always meet NHS-recognised diagnostic standards. 

4. After Diagnosis or While Waiting 

Following diagnosis, NICE recommends developing a personalised support plan within a few weeks, including access to education, communication, or behavioural support. 
For those waiting, the National Autistic Society provides guidance on practical steps to take, and local NHS trusts may offer interim advice or family support. 
The UK Autism Strategy (2021–2026) also commits new funding to reduce delays and improve post-diagnostic care (Department of Health and Social Care). 

Takeaway 

While NICE guidance sets a 13-week benchmark, most people in England currently wait much longer for an autism assessment, often many months. It’s reasonable to contact your GP or local service to check expected timelines, ask about interim support, and ensure your referral remains active.