Medical Necessity Denials
CARC 50CARC 151The payer determined the service was not medically necessary per its policy.
What it is
The pattern
A medical-necessity denial means the payer reviewed the service against its coverage policy and concluded it was not reasonable and necessary — often because the documentation does not establish the clinical picture the policy requires.
Why it happens
Common causes
- The documentation focuses on what was done, not why it was medically needed.
- The diagnosis code does not support the service (or the specificity is missing).
- The policy requires certain clinical criteria and the record does not address them.
- The service was performed before the policy's required pre-service review.
Prevention
Stop it before the claim goes out
- Know the payer policy for high-review services before rendering — what clinical criteria it names.
- Document the medical rationale in the record at the time of service, not after the denial.
- Make sure the diagnosis and service codes tell the same clinical story.
When it happens
What to do
Appeal with the clinical documentation that addresses the policy's criteria directly — a narrative that restates the policy requirement and points to the record page that meets it. A general 'the service was necessary' letter rarely wins; a criterion-by-criterion response does.
Deeper dive
The full denial guide
The payer determined the service was not medically necessary or reasonable according to its policy. These denials are documentation-driven.
Open the Medical Necessity guide →