Insurance Denied as "Not Medically Necessary"? Here's How to Fight It

What "Not Medically Necessary" Actually Means

When an insurer denies a claim as "not medically necessary," they're saying that based on their review of the available information, the requested service or treatment doesn't meet the specific clinical criteria they use to determine medical necessity.

This determination is not arbitrary — insurers use specific, published clinical criteria sets to make these decisions:

• MCG Guidelines (formerly Milliman Care Guidelines) — widely used by commercial insurers
• InterQual Criteria — used by UnitedHealthcare, Cigna, and others
• CMS NCDs/LCDs — National and Local Coverage Determinations for Medicare and Medicaid

However, these criteria don't capture every patient's unique clinical situation. That's why the appeal process exists — and why these denials are frequently overturned when the appeal includes the right information.

Why This Denial Reason Is Often Overturned

Medical necessity denials are among the most commonly overturned denial types on appeal, according to industry reports. The most common reasons these denials are reversed include:

• The initial review was based on incomplete information — the appeal provides additional clinical documentation
• The treating physician's rationale wasn't included in the original submission
• The patient's case actually does meet the criteria when the full clinical picture is presented

According to KFF's research on ACA marketplace plans, while most denied claims are never appealed, those that are appealed have a meaningful rate of being overturned — particularly when the appeal addresses the specific clinical criteria used in the denial.

The 3 Things Your Appeal Must Prove

1. Your Treating Physician's Clinical Rationale

A letter from your treating physician explaining, in clinical detail, why this treatment is medically necessary for your specific situation. This should include diagnosis, clinical findings, and the expected outcome of the proposed treatment.

2. That Alternative Treatments Were Tried and Failed

If applicable, document that conservative or alternative treatments were tried first and were unsuccessful. Many clinical criteria require evidence of "step therapy" — trying less intensive treatments before more expensive options are approved.

3. That Your Case Meets the Specific Published Criteria

This is the critical piece. You need to identify the exact criteriayour insurer applied and demonstrate — point by point — how your case meets each requirement. Generic statements won't work; specific guideline citations will.

How to Find Your Insurer's Specific Criteria

Many major insurers publish their medical policies and clinical policy bulletins online. You can search for the specific criteria that applies to your denied treatment:

• Aetna — publishes Clinical Policy Bulletins (CPBs) at aetna.com
• Anthem/Elevance — publishes Medical Policies searchable online
• UnitedHealthcare — publishes Medical Policies and Coverage Determination Guidelines
• CMS (Medicare) — publishes NCDs and LCDs searchable at cms.gov/medicare-coverage-database

Common Mistakes That Get These Appeals Rejected Again

Generic "My Doctor Says I Need This" Language

Simply stating that your doctor recommends a treatment is not enough. The appeal needs to explain why in clinical terms, with specific reference to the criteria used for the denial.

Missing Specific Guideline Citations

An appeal that doesn't reference the specific clinical criteria your insurer used is essentially arguing blind. You need to name the criteria set, edition, and specific criterion number.

Not Addressing the Specific Denial Reason

Your appeal must respond to the specific reasonstated in your denial letter. If the denial says you didn't meet criterion X, your appeal needs to demonstrate that you do meet criterion X — not argue about criteria Y and Z. For a complete guide on structuring your appeal, see our appeal letter writing guide.

Make sure you understand your appeal deadlines and know the difference between internal appeals and external reviews before you begin.

Let AI Find the Right Guidelines and Write the Letter

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