How to Get an Adult Autism Diagnosis in the UK

Step 1: Speak to Your GP

Your GP is the usual starting point for an autism assessment referral in the UK. NICE guideline CG142 states that GPs should refer adults who show signs of autism for a specialist assessment, even without a formal screening score.

Before your appointment, prepare a written list of specific examples showing how autistic traits affect your daily life. Think about difficulties with social communication, sensory sensitivities, need for routine, and how you managed as a child versus now. If you have completed an online screening tool such as the AQ-10 or RAADS-R, bring the results along.

Be direct with your GP: “I believe I may be autistic and I would like a referral for a specialist assessment.” If your GP suggests that you “don't look autistic” or that you “coped fine at school,” you are within your rights to insist on a referral. Masking is well-documented in the clinical literature, particularly among late-diagnosed adults.

Step 2: NHS Assessment Pathway

Once your GP makes a referral, you will be placed on the waiting list for your local NHS autism assessment service. The service is usually run by a community mental health team or a specialist autism diagnostic service commissioned by your Integrated Care Board (ICB).

Waiting times vary enormously. Some areas assess within 12 months; others have waits exceeding 5 years. According to the Nuffield Trust, the median wait for an adult autism assessment in England is now over 3 years in many Integrated Care Board areas. The NICE guideline NG170 recommends that assessments begin within 13 weeks of referral, but this target is rarely met in practice. For strategies while you wait, see our NHS autism waiting list guide. You can contact your local service directly to ask for an estimated timeframe.

The assessment itself typically involves a clinical interview covering your developmental history, current difficulties, and strengths. Many services ask for an informant report from a parent, partner, or someone who knew you in childhood. Some use standardised diagnostic instruments such as ADOS-2 or ADI-R, while others rely on clinical judgement structured around DSM-5 or ICD-11 criteria.

Step 3: Right to Choose

The NHS Constitution (Section 3.5) gives you the legal right to choose any qualified provider for your first outpatient appointment. This includes autism diagnostic assessments. In practice, this means your GP can refer you to a private provider that holds an NHS contract, and the NHS pays for the assessment.

Providers commonly used through the Right to Choose pathway include Psychiatry-UK and Clinical Partners, among others. Waiting times through these providers are typically shorter than local NHS services, often between 6 and 18 months, though this fluctuates with demand.

To use Right to Choose, ask your GP to make the referral directly to your chosen provider. If your GP is unsure about the process or reluctant, you can point them to NHS England's guidance on patient choice and the provider's own GP referral information page. Some ICBs have been known to push back, but the legal position is clear: this right applies to autism assessments.

Note that Right to Choose applies in England. Scotland, Wales, and Northern Ireland have different healthcare frameworks and this specific pathway is not available in those nations, though each has its own referral processes.

Step 4: Private Assessment

If NHS and Right to Choose waiting times are unacceptable and you have the financial means, a private autism assessment is another option. Costs typically range from £800 to £2,500, depending on the provider and assessment format.

When choosing a private provider, check the following: the assessing clinician should be a registered psychiatrist, clinical psychologist, or specialist practitioner with specific experience in adult autism. The assessment should follow NICE guideline CG142 and use recognised diagnostic frameworks. Ask whether the assessment includes a developmental history, informant input, and a structured clinical observation.

A private diagnosis holds the same clinical validity as an NHS diagnosis. However, some NHS services or local authorities may request their own assessment before offering post-diagnostic support. It is worth asking your ICB about their policy on accepting private diagnoses before committing to a provider.

What Happens During an Autism Assessment?

An adult autism assessment is a detailed clinical evaluation, not a quick test. It typically lasts between 2 and 4 hours and may be conducted across multiple sessions.

Developmental history: The clinician will ask about your early childhood, school years, friendships, and family life. This is where informant evidence is valuable — a parent or older sibling who can describe your behaviour as a child strengthens the assessment considerably.

ADOS-2 (Autism Diagnostic Observation Schedule): A semi-structured interaction where the clinician presents social scenarios and observes your responses. Not all services use ADOS-2 for adults, but it remains one of the gold-standard diagnostic tools.

ADI-R (Autism Diagnostic Interview – Revised): A structured interview, usually conducted with an informant, covering communication, social interaction, and repetitive behaviours throughout your life.

Multi-informant evidence: Clinicians gather evidence from multiple sources — your own account, informant reports, school records if available, and their clinical observations. This triangulation of evidence is a core principle of thorough autism assessment as recommended by NICE.

What You Can Do Right Now

Regardless of which assessment pathway you choose, there are steps you can take today to move the process forward and support yourself along the way.

• Book a GP appointment. Prepare a written list of specific examples showing how autistic traits affect your daily life, and ask directly for a referral to an autism assessment service.
• Start gathering evidence now. Keep a journal of situations where you notice social communication differences, sensory sensitivities, or need for routine. Ask a parent or partner if they would be willing to contribute their observations.
• Connect with the autistic community. The National Autistic Society, local peer groups, and online forums can provide practical advice and emotional support throughout the assessment process.

AskSheldon also offers free tools to support your assessment journey:

Pre-assessment screening: Complete clinically-informed screening questionnaires that help you understand whether your experiences align with autistic traits. The results can be shared with your GP or clinician to support your referral.

Evidence gathering: AskSheldon's diagnostic assessment uses five independent AI agents in a multi-disciplinary team analysis, mirroring how clinical MDTs work. It extracts structured evidence from your responses and supports multi-informant input from parents, partners, and other people who know you well.

Frequently Asked Questions