CO-50: Not deemed a medical necessity

Why this denial happens

• The claim was submitted without the chart notes, imaging report, or conservative-care history the payer's medical policy requires.
• The CPT/HCPCS code billed doesn't match the diagnosis (ICD-10) code in a way the payer's edits recognize.
• The plan's medical policy requires step therapy (e.g., 6 weeks of PT before an MRI) and the records don't show it was tried.
• The reviewer applied the wrong medical policy version or used InterQual/MCG criteria that don't fit the patient's situation.

How to fix or appeal CO-50

1. Request the specific medical policy and the reviewer's notes in writing - payers must provide them on request.
2. Ask your provider for a letter of medical necessity that maps each plan-policy criterion to a line in your chart.
3. Attach prior conservative treatment records (PT, medications tried, imaging) to show step therapy was satisfied.
4. File a first-level internal appeal within the deadline on your denial (usually 180 days for commercial, 60 for Medicare).
5. If the internal appeal fails, request an external/independent review - overturn rates exceed 40% on well-documented medical-necessity cases.

Related denial codes

• CO-197 - Precertification/authorization absent
• CO-11 - Diagnosis inconsistent with procedure

Insurer-specific appeal guides

• How to appeal a medical necessity denial from Aetna
• How to appeal a out-of-network denial from UnitedHealthcare
• How to appeal a prior authorization denial from Cigna