Q: Do I need a diagnosis for insurance to cover therapy?
A: In practice, yes — a claim carries a diagnosis code, so somebody has to write one down. What changed in California is how little room the plan has to argue about it. Since 1 January 2021, commercial plans must cover all mental health and substance use disorders listed in the current DSM or ICD, not just a short list of severe illnesses, and must judge medical necessity against treatment criteria written by the nonprofit professional association for that speciality — not against criteria the plan invented.¹ "You have anxiety but not badly enough" is a much harder position for an insurer to hold than most people assume.
Worked example: a plan denies your eighth session as "not medically necessary." Under the California standard, the denial has to rest on the relevant nonprofit association's criteria, and it has to be about your clinical need rather than the plan's cost. That is an appealable letter, not a verdict — and the appeal is free.
Do this: ask your therapist which code they submit and what it means; you are entitled to know what is on your own claim. What a diagnosis code actually is → If a session is denied, ask the plan in writing which criteria it applied and who wrote them — then take it to the DMHC Help Center, 888-466-2219, which runs a free independent medical review. The appeal, step by step →
Sources
- SB 855 (2019–2020), effective for plans issued, amended or renewed on or after 1 January 2021: coverage of all mental health and substance use disorders in the most recent DSM or ICD, statutory medical-necessity definition, and mandated use of nonprofit clinical-speciality criteria — leginfo.legislature.ca.gov; analysis at manatt.com. Verified 17 August 2026.