Yes — if their ADHD has a substantial, long-term adverse effect on day-to-day activities, it is a disability under the Equality Act 2010 and protected from discrimination. It is assessed individually, not automatic. ADHD is not named in the Act, so it is not a disability by default; it qualifies when it meets the legal test, and when it does, your employee is protected whether or not they have ever called themselves disabled.
The eligibility rule: the section 6 test
A person is disabled in law if they have a physical or mental impairment that has a substantial and long-term adverse effect on their ability to carry out normal day-to-day activities (section 6 of the Equality Act 2010). "Substantial" means more than minor or trivial. "Long-term" means it has lasted, or is expected to last, at least 12 months or for the rest of the person's life. ADHD often clears this bar, but you apply the test to the individual in front of you, not to the label.
What this means for your exposure as the employer
Once an employee's ADHD is a disability, three claims become live. They can bring direct discrimination if they are treated less favourably because of disability (section 13); discrimination arising from disability if they are treated unfavourably because of something connected to it, such as lateness, missed deadlines or a blunt email, and you cannot objectively justify that treatment (section 15); and a failure to make reasonable adjustments where a way you work puts them at a substantial disadvantage (section 20). All of these sit inside the employment field under section 39, so they apply from recruitment through to dismissal.
Two qualifiers the headline guidance tends to miss, and both raise your risk. First, a formal diagnosis is not required. Acas is clear that someone does not need a medical diagnosis to be disabled in law, and that neurodivergence will often amount to a disability even where the person does not think of themselves that way. Second, a 2025 Employment Appeal Tribunal ruling (Stedman v Haven Leisure) has lowered the practical bar. Where there is a clinical ADHD diagnosis, a tribunal must treat it as relevant evidence of impact; a substantial effect on a single day-to-day activity is enough; and the tribunal must not weigh what the employee can do against what they cannot. The comparison is the employee with the impairment versus how they would be without it.
The practical upshot: assuming "their ADHD seems mild, so it won't qualify" is now a weak bet. Coping strategies your employee has built, and the tasks they handle well, do not take them outside the Act.
Qualifying is not the same as winning
Being disabled brings the employee within scope; it does not decide a claim. A tribunal still asks whether the treatment happened, whether it was because of disability or something arising from it, and whether you acted reasonably. So protection cuts both ways: it is your route to a defence as much as their route to a claim. The defensible position is to treat a disclosure as a trigger to act, not a threat to manage.
Where the law comes from
Related
This page is general information, not clinical or legal advice.