“Not medically necessary” is one of the most common — and most appealable — denial reasons. The insurer is second-guessing your treating clinician’s judgment, so the winning move is to put the clinical case in front of them: your physician’s reasoning, your history, what was tried before, and the guidelines that support the treatment.
What makes this appeal work
- A letter of medical necessity from your treating provider (the single most important attachment).
- History: prior treatments tried and why they failed or weren’t appropriate.
- Evidence: relevant clinical guidelines, the plan’s own medical policy, and records/test results.
The letter (your cover letter; attach your doctor’s)
[Your full name]
[Your address]
[City, State ZIP]
[Phone] | [Email]
[Date]
[Insurance company - Appeals Department]
[Address from your denial letter]
Re: Appeal of "not medically necessary" denial
Member: [Name] Member ID: [number]
Claim / prior-auth number: [number] Date(s) of service: [dates]
Service denied: [name of procedure, drug, test, or admission]
To the Appeals Department:
This claim was denied as "not medically necessary." I am appealing, and I ask
that a physician in the relevant specialty review it.
This treatment is medically necessary for me because:
[Summarize your provider's reasoning - the condition being treated, why this
service is appropriate, and what was tried first. Keep it brief; the details
are in the attached letter of medical necessity.]
Enclosed in support:
- Letter of medical necessity from [Dr. name, specialty]
- Records of prior treatments tried: [list]
- Test results / imaging supporting the diagnosis
- [Clinical guideline or your plan's medical policy supporting this service]
Please overturn the denial and approve coverage. If you uphold it, please send
the clinical rationale and the credentials of the reviewer, and explain how to
request an external review.
Sincerely,
[Your signature]
[Your printed name]
How to send it
File within your plan’s appeal deadline (often 180 days). Ask your doctor’s office to send the letter of medical necessity — they write these routinely. If the treatment is urgent, request an expedited appeal. Send certified or through the official channel and keep copies.
Notes. Ask the insurer for a peer-to-peer review, where your doctor speaks directly with the plan’s medical reviewer — it often resolves these faster. If the internal appeal is upheld, escalate to an external review, where an independent physician decides. This is general information, not legal or medical advice; your clinician guides the medical content.