How to appeal a “Not medically necessary” denial
A 'not medically necessary' denial means your insurer's reviewer decided the treatment your doctor ordered isn't needed for your condition — even though they never examined you. It's one of the most common denials, and also one of the most winnable, because it comes down to clinical evidence you and your provider can supply.
The key is to move the decision back to documented medical facts: your diagnosis, what you've already tried, and why this specific care is the appropriate next step under accepted standards of care.
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Why insurers issue this denial
- The service didn't match the insurer's internal clinical criteria for your diagnosis.
- Required step-therapy or conservative treatment wasn't documented as tried first.
- The submitted records were incomplete, so the reviewer couldn't see the full clinical picture.
- An automated or non-specialist review flagged the claim without a detailed chart review.
How to appeal, step by step
- 1Request the specific clinical criteria and plan provisions the insurer used to deny the claim.
- 2Ask your treating provider for a letter of medical necessity that ties your diagnosis and history to the requested care.
- 3Gather records showing what you've already tried and how you responded.
- 4Submit a written appeal that answers the insurer's stated criteria point by point, before your deadline.
- 5If it's upheld, request review by a board-certified specialist and pursue independent external review.
Evidence that strengthens your appeal
- A letter of medical necessity from your treating provider (the single most effective document).
- Chart notes, test results, and imaging that document your condition.
- A record of prior treatments tried and their outcomes.
- Published clinical guidelines for your diagnosis that support the treatment.
Common mistakes to avoid
- Appealing with emotion instead of clinical documentation.
- Missing the filing deadline stated on your denial letter.
- Not asking for the exact criteria the insurer used, so your appeal can't rebut it.
- Sending records without a provider letter connecting them to medical necessity.
Frequently asked questions
What does 'not medically necessary' actually mean?
It means the insurer's reviewer concluded the care isn't required to diagnose or treat your condition under their clinical criteria. It's a coverage decision, not a medical one, and you can appeal it with documentation from the provider who actually treats you.
How do I prove medical necessity?
The strongest proof is a letter of medical necessity from your treating provider that connects your diagnosis, history, and prior treatments to the requested care, supported by chart notes and recognized clinical guidelines.
How long do I have to appeal?
It depends on your plan — commonly 180 days for employer (ERISA) and ACA plans, and shorter for some Medicare and Medicaid plans. Check your denial letter for the exact deadline, or use our deadline calculator.
What if my appeal is denied again?
You can usually request a second-level internal review and then an independent external review by a reviewer not affiliated with your insurer. Our generator creates an escalation letter for exactly this step.
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Important: this is not legal or medical advice.
AppealBrain is a free, self-help tool that helps you draft an appeal letter using the information you provide. We are not a law firm, medical provider, or insurance company, and using this tool does not create an attorney–client relationship. Appeal rules and deadlines vary by plan and state — always review your own denial letter and plan documents, and consider consulting a licensed professional for your specific situation. We do not guarantee any outcome.