1.2 Diagnosis

A Diagnostic Assessment is usually carried out from the age of seven onwards to adults to comply with SASC guidelines (SpLD Assessment Standards Committee – this is the governing body for specialist teacher assessors). A lot of reading and writing is involved in a full diagnostic assessment with up to three or more hours of tests, so it could be inappropriate to put a child younger than seven years old through this, especially as some children are later to read than others.

A diagnosis of dyslexia needs to be carried out by a qualified professional, a specialist dyslexia support teacher or an educational psychologist, and produces an in-depth diagnostic picture, based on a battery of tests carried out to identify strengths and weaknesses in reading, writing, working memory and speed of processing. This process involves quantitative (measurable) data that has been collected alongside qualitative (background) information. To make sure that any literacy difficulties are not down to a visual issue, the person being assessed should have had a sight test in the two years before an assessment takes place.

A diagnosis can be expensive. At the time of writing (in 2025), the ranging price varies from £500-600 upwards and is usually self-funded (paid by an individual, parent or employer), although some charities, such as British Dyslexia Association and Helen Arkell Dyslexia Charity, can subsidise. See links below for some further information.

The rest of this section will explore the need for diagnosis and the process more deeply, as it’s crucial to understand its importance.