Can my employer ask for a diagnosis?

When can they ask at all?

If your disability and your need for the accommodation are obvious or already known — say you use a wheelchair and ask for a ramp — your employer generally cannot ask you to prove it. They can ask for reasonable documentation only when the disability, or the need for the specific accommodation, isn't obvious. (EEOC Enforcement Guidance on Reasonable Accommodation.)

What can they actually ask for?

"Reasonable documentation" means just enough to establish that you have a disability under the ADA and that it requires the accommodation. A note from an appropriate professional that describes your functional limitations and connects them to the requested accommodation is typically enough — it does not have to state your diagnosis. They can't require your complete medical history or details about conditions unrelated to the accommodation.

What they can't do

• Ask for documentation when your disability and need are obvious or already known.
• Demand your entire medical record, or ask about unrelated conditions.
• Insist on a specific diagnosis when functional documentation already substantiates the disability and need.
• Share your medical information — under the ADA it must be kept confidential, in separate files.

The practical move

You can usually satisfy a request with a short letter from your provider that describes what you have difficulty with and why the accommodation helps — framed around the functional limitation, not the diagnosis. That's also exactly how a strong accommodation request reads.