Why Was My Insurance Claim Denied for Being 'Not Medically Necessary'?

By The Penny Plan Editorial Team Published July 13, 2026 6 min read

A doctor recommends a procedure, it gets scheduled, and then a letter arrives saying the insurer won’t pay because the care wasn’t “medically necessary” — a phrase that feels almost insulting when a licensed physician is the one who suggested it in the first place.

The short answer

“Not medically necessary” is a specific insurance term, and it generally means the documentation submitted didn’t satisfy the insurer’s own internal criteria for that particular treatment, not that a reviewer is overriding a doctor’s clinical judgment out of nowhere. Insurers typically apply written coverage policies with defined requirements — prior tests, documented symptoms, tried-and-failed alternative treatments — and a denial often means one of those specific boxes wasn’t checked in the paperwork, even when the underlying medical reasoning was sound.

Why this disconnect happens

A treating doctor decides what’s clinically appropriate based on a full picture of a patient. An insurer’s medical necessity review is usually a narrower, checklist-based process applied to whatever was documented in the claim, sometimes by a reviewer who never examines the patient directly. If a note doesn’t explicitly state that a more conservative treatment was tried first, or doesn’t document a specific symptom the insurer’s policy requires, the claim can be denied on paper even though the clinical decision was reasonable. This is a documentation gap as much as it is a medical disagreement.

Where the criteria actually come from

Coverage rules vary by insurer and, for employer-sponsored plans, can also vary based on what a specific employer selected when structuring the plan, which is why two people with the same diagnosis at different companies can see different outcomes. Government programs and private insurers each maintain their own separate sets of medical necessity criteria, and neither is a single universal standard applied identically everywhere.

Steps generally available after a denial

Requesting the specific denial reason in writing. Insurers are generally required to state why a claim was denied, including which criteria were not met.
Asking the provider’s office for additional documentation. Sometimes the original claim simply lacked detail that a corrected note can supply.
Filing an internal appeal. Most plans have a formal appeals process, often with a defined window to file.
Requesting an external review. Many plans allow an independent third party to review a denial after internal appeals are exhausted, separate from the insurer itself.

A denial for one procedure doesn’t necessarily mean every related expense is affected, and it’s worth separately tracking what counts toward an out-of-pocket maximum for the plan year, since a denied claim generally isn’t counted there either. Some medically necessary care disputes intersect with billing issues entirely apart from the necessity question, which is part of why protections against surprise medical bills exist as a separate framework. And in situations involving extended recovery time from a denied procedure, some people also end up navigating doctor paperwork for a short-term disability claim, which runs on its own separate documentation track.

The bottom line

A “not medically necessary” denial is frustrating precisely because it can feel like a paperwork technicality overriding a real clinical decision — and often, that’s close to accurate. The path forward generally runs through documentation: getting the specific criteria in writing, working with the provider’s office to address any gaps, and using the formal appeal process rather than treating the first denial as final. Coverage criteria and appeal windows vary enough by plan that checking the specific plan documents is a more reliable guide than assuming the process works the same way everywhere.