A medical necessity denial means the health plan (UnitedHealthcare, Aetna, Cigna, Anthem/Elevance, a Blue Cross Blue Shield licensee, Kaiser, or a marketplace insurer) says the service, drug, or device is not needed under its clinical criteria, even even if your clinician recommended it. That is different from a billing typo, an out-of-network surprise, or a deductible you simply owe.
This guide covers how necessity appeals work, what to gather, and how they sit next to prior authorization and claim denials.
Necessity vs other denial reasons
| Denial flavor | Typical meaning | First move |
|---|---|---|
| Not medically necessary / experimental | Plan criteria say the care is not covered at your stage | Necessity appeal with clinical notes |
| Prior auth missing or mismatched | Approval was never obtained or details differ | Fix auth or appeal the auth denial (Prior authorization) |
| Coding / eligibility / timely filing | Paperwork or membership issue | Correct and resubmit (Denied insurance claims) |
| Non-covered benefit | Plan excludes the category entirely | Check SPD/EOC; appeal only if exclusion was misapplied |
Read the denial letter and the explanation of benefits together. Match CPT/HCPCS and drug names to what your clinician ordered. Broader bill hygiene: Medical bills and insurance.
How a medical necessity appeal usually runs
- Internal appeal with the plan within the deadline printed on the letter (often 180 days for post-service; urgent care can be much shorter).
- Clinician submits a letter of medical necessity, chart notes, labs, imaging, and peer-reviewed support when relevant.
- Plan’s medical reviewers respond in writing with uphold or overturn.
- If upheld, many plans allow external review by an independent reviewer under state or federal rules (Affordable Care Act marketplace and many employer plans).
Drug formulary fights sometimes use a parallel formulary exception path (Formulary exceptions) that still leans on necessity language.
Worked example
Maya’s orthopedist recommends an MRI after six weeks of physical therapy for a knee injury. The plan denies the MRI as “not medically necessary” without updated imaging. The clinic submits an appeal with therapy notes, exam findings, and the orthopedist’s letter citing plan criteria for persistent symptoms. The internal appeal overturns the denial; the MRI is approved as a covered in-network service.
Maya still owes deductible and coinsurance on the MRI. That patient share is a bill problem, not a second necessity appeal. Negotiate negotiate or plan-pay with Negotiating medical bills if the balance is painful after insurance processes.
What you can do while the clinician leads
- Calendar the appeal deadline the day the letter arrives.
- Request the plan’s clinical criteria or medical policy for that CPT/drug (many post them in member portals).
- Ask the clinic who owns the submission and for a copy of what they send.
- Keep paying unrelated undisputed bills so collections do not start on the wrong balance.
- Do not ignore a concurrent prior-auth requirement on a related procedure.
For the layered appeal stack after any denial type, use How to handle a denied insurance claim.
Checklist
- Separate “not medically necessary” from coding, network, and deductible issues.
- Save denial letter, EOB, and plan medical policy PDFs in one folder.
- Ask the ordering clinician for a letter of medical necessity and supporting notes.
- File or confirm the internal appeal before the printed deadline.
- If upheld, ask member services for external review instructions in writing.
- Budget patient-share costs separately; appeal coverage first, then negotiate leftovers.
Educational only. Not medical, legal, or insurance advice. Appeal rights, deadlines, and external review rules vary by plan and state.