Dyslexia Screening vs Assessment: Which Does My Child Need?
Updated: Oct 28
Dyslexia screening and a diagnostic assessment answer different questions. Screening can indicate possible difficulties and help guide a next step. A diagnostic assessment investigates the wider learning profile and whether the evidence supports a diagnosis. Choosing between them starts with what you want to find out.
What can dyslexia screening tell you?
A screening appointment offers a shorter look at selected skills. Its findings can help you decide whether further investigation would be useful, but they cannot confirm or rule out dyslexia with certainty. A screening result should be considered alongside the difficulties noticed at home or in education.
At Dyslexia Tests Online, the £50 TOD-S screening service is conducted live online with Mark Trewby for ages 8–21. It takes approximately 20–30 minutes and includes a written screening summary within 24 hours. It is a professional appointment, rather than a free self-completed quiz.
What does a diagnostic assessment add?
A diagnostic assessment brings together background information, educational history and a broader range of assessment findings. The written report explains the conclusions and recommendations. A brief screener cannot provide the same depth of investigation or replace a diagnostic report.
Mark’s full assessment costs £400, including the assessment, personalised report, recommendations and feedback. The assessment appointment normally takes approximately three hours, and the diagnostic report is provided within seven working days.
Which question are you trying to answer?
“We have concerns and want an initial discussion of possible dyslexia risk.” Screening may be a useful option to discuss.
“We want to investigate whether these persistent difficulties are consistent with dyslexia.” Ask about a full diagnostic assessment.
“We need evidence for a particular purpose.” Check the receiving organisation’s requirements before paying for either service.
“We already have screening results but still have concerns.” Share the results and the history with the assessor before booking another appointment.
Screening is not a compulsory first purchase before a full assessment. If you already know that you want diagnostic investigation, ask directly about that route. Equally, a screening result does not mean you must immediately buy a full assessment.
Do you need to wait for a diagnosis before seeking support?
You can discuss reading, spelling and written-work difficulties with the school while considering assessment. The British Dyslexia Association explains that schools can put support in place without waiting for a formal diagnosis. Share specific examples of what is difficult and ask what support is available.
How do Mark’s fees work if you choose both?
If you proceed to Mark’s £400 diagnostic assessment within 30 days of the £50 screening, the screening fee is credited towards it. You pay a further £350, making £400 in total across the two services. This credit does not change what screening can establish.
Check age and appointment options
Online diagnostic assessments are available across the UK for ages 11–21. Face-to-face diagnostic assessments are available in Bournemouth for ages 8–21, in a suitable client home or a hired Bournemouth library room. Screening is available online for ages 8–21. Suitability is discussed before booking.