ADHD & Autism Assessment in the UK:
Your Complete Guide (2026)

An ADHD assessment is a structured clinical evaluation carried out by a trained professional — usually a psychiatrist, psychologist, or specialist nurse — to determine whether someone meets the diagnostic criteria for Attention Deficit Hyperactivity Disorder (ADHD) as defined by DSM-5 or ICD-10/11.

The assessment looks at your history of attention difficulties, hyperactivity, impulsivity, and executive function across different settings (home, school, work). Clinicians use standardised rating scales and a detailed clinical interview to build a full picture before reaching a diagnosis.

ADHD is one of the most common neurodevelopmental conditions, affecting an estimated 5% of children and 3–4% of adults in the UK. Despite its prevalence, diagnosis can be difficult to access quickly through the NHS — which is why routes like NHS Right to Choose and private assessment have become increasingly important.

An autism assessment is a specialist evaluation that determines whether someone meets the diagnostic criteria for Autism Spectrum Disorder (ASD), as defined by ICD-10/11 or DSM-5. The term "autism spectrum" reflects the wide variation in how autism presents — from highly verbal adults to non-speaking children, and everyone in between.

A gold-standard autism assessment uses two validated tools: the ADOS-2 (Autism Diagnostic Observation Schedule, 2nd edition), which involves structured observation of the person, and the ADI-R (Autism Diagnostic Interview — Revised), a developmental interview with a parent, carer, or the person themselves. Not all private providers use both instruments — it is worth asking before booking.

Many people seeking an autism assessment are also assessed for ADHD in the same process. This is called an AuDHD assessment and can be more cost-effective than two separate assessments. Research suggests that around 50–70% of autistic people also have ADHD and vice versa.

NHS Right to Choose is a policy in England, set out in the NHS Constitution, that allows patients to ask their GP to refer them to any CQC-registered provider for a specialist assessment — including ADHD — at no cost to the patient. The NHS funds the entire assessment.

Not all CQC-registered providers accept NHS Right to Choose funding — Seen Sooner filters to show only those that do, ranked by wait time and service rating.

A fully private ADHD assessment is paid for by you and requires no GP referral at most providers. It is the fastest route to a diagnosis, typically available within 2–6 weeks.

Private assessments are conducted by the same types of clinicians (psychiatrists, psychologists) as NHS assessments and follow the same diagnostic criteria. A diagnosis from a CQC-registered private provider carries the same clinical validity as an NHS diagnosis.

The cost of a private ADHD assessment varies considerably by provider, type (adult/child), and format (online/in-person). Here is a typical cost breakdown.

Standard NHS waiting times for ADHD assessment have grown significantly in recent years. Some NHS Trusts have waiting lists of three to five years for adults and even longer for children in some areas. These delays are why NHS Right to Choose and private routes have become so important.

Right to Choose wait times vary by provider — typically 12 to 24 weeks — as providers must allocate funded NHS slots alongside private bookings. Private assessment is the fastest route, with most providers able to offer an appointment within two to six weeks of enquiry.

Children under 18 can be assessed for ADHD through both NHS and private routes. In England, NHS Right to Choose applies to children as well as adults, though fewer providers accept under-18s via this route.

NHS CAMHS (Child and Adolescent Mental Health Services) provides the standard route for children in all four UK nations. CAMHS waits for ADHD assessment are among the longest in the NHS — some areas report waits exceeding five years.

A UK ADHD assessment typically takes place across one to three appointments and follows a structured process.

1. 1

   1. Pre-assessment questionnaires

   You will complete standardised rating scales before your appointment — typically the Conners Adult ADHD Rating Scales (CAARS), DIVA-5 questionnaire, or similar tools. For children, a teacher questionnaire is also usually required.

2. 2

   2. Clinical interview

   A psychiatrist or specialist nurse conducts a structured interview covering your developmental history, symptoms across different environments, and the impact on your daily life. For children, a parent/carer is usually interviewed separately.

3. 3

   3. Cognitive or neuropsychological testing (where applicable)

   Some providers include cognitive testing (such as Qbtest or CPT) to support the diagnosis. This is not always required but can be useful for complex presentations.

4. 4

   4. Diagnostic report

   The clinician reviews all information and issues a diagnostic report, usually within 1–4 weeks. The report confirms or rules out ADHD and may make recommendations for medication, therapy, or workplace/school adjustments.

5. 5

   5. Medication titration (if ADHD is confirmed)

   If you are diagnosed and wish to explore medication, a titration phase begins. A stimulant or non-stimulant is started at a low dose and adjusted over several weeks. Once stable, prescribing is ideally transferred to your NHS GP under a shared care agreement.

An ADHD diagnosis opens access to a range of support. Here is what to expect next.