Denial codes / CO-50
CO-50 denial: meaning, fix & appeal letter template
Payer says the service wasn't medically necessary.
What it means
Official CARC 50 descriptionThese are non-covered services because this is not deemed a 'medical necessity' by the payer.
The payer decided the documentation didn't meet its medical-necessity criteria for the service. These are among the most winnable denials when the clinical record actually supports the criteria — the appeal has to map the record to the policy point by point.
Common causes
- Documentation doesn't show the payer's required criteria (e.g. failed conservative therapy, red-flag symptoms)
- Diagnosis coded doesn't match the LCD/policy's covered indications
- Frequency limit exceeded without documented reason
- Relevant records (PT notes, imaging, labs) not sent with the claim
- Payer applied internal criteria stricter than Medicare (Medicare Advantage)
How to fix it
- Pull the payer's medical policy (or the LCD/NCD) for the CPT and list each criterion
- Map each criterion to a specific line in the clinical record
- Get a letter of medical necessity from the treating physician if criteria are implicit
- Check coding — a more specific diagnosis may meet criteria
- Request a peer-to-peer review where the payer offers it
Appeal or corrected claim?
Appeal. A corrected claim won't help unless coding was wrong. File a first-level appeal that quotes the payer's criteria and points to the documentation meeting each one. If denied again, escalate to second-level or external review.
Medicare Advantage note
For Medicare Advantage plans, 42 CFR 422.101(b)(6) requires MA organizations to follow traditional Medicare coverage criteria, including NCDs and LCDs, and limits when they can apply their own internal criteria. If the service meets the applicable NCD/LCD, cite this in the appeal. Verify the current regulation text before citing.
What to attach
- Office/consult notes documenting symptoms, duration, and prior treatment
- Results of prior conservative treatment (PT notes, medication history)
- Letter of medical necessity from the ordering physician
- Payer medical policy or LCD/NCD excerpt with criteria highlighted
CO-50 appeal letter template
Replace every [BRACKETED] field. Remove any optional paragraph that doesn't apply.
[PRACTICE NAME] [ADDRESS] · [PHONE] · NPI [NPI] · TIN [TIN] [DATE] [PAYER NAME] Attn: Appeals / Provider Disputes [PAYER APPEALS ADDRESS] Re: Request for Reconsideration — Claim [CLAIM NUMBER] Patient: [PATIENT NAME] Member ID: [MEMBER ID] DOB: [DOB] Date of Service: [DOS] CPT: [CPT CODE] Billed: [AMOUNT] Denial: CO-50 — These are non-covered services because this is not deemed a 'medical necessity' by the payer. Dear Appeals Reviewer, We request reconsideration of the denial of the above claim. The above service was denied with CARC 50, indicating it was not deemed medically necessary. We disagree. [PAYER NAME] policy [POLICY NAME/NUMBER] [or LCD L[NUMBER]] covers CPT [CPT CODE] when [CRITERIA SUMMARY]. The enclosed records show each criterion was met: 1. [CRITERION 1] — documented in [NOTE], dated [DATE]: "[QUOTE]" 2. [CRITERION 2] — documented in [NOTE], dated [DATE]: "[QUOTE]" 3. [CRITERION 3] — documented in [NOTE], dated [DATE]: "[QUOTE]" [For Medicare Advantage: Under 42 CFR 422.101(b)(6), [PAYER NAME] must apply traditional Medicare coverage criteria. This service meets [NCD/LCD NUMBER].] The treating physician's letter of medical necessity is enclosed. Based on the enclosed documentation, we request that [PAYER NAME] overturn this denial and reprocess the claim for payment in accordance with the member's benefits and our participation agreement. Enclosures: - Office/consult notes documenting symptoms, duration, and prior treatment - Results of prior conservative treatment (PT notes, medication history) - Letter of medical necessity from the ordering physician - Payer medical policy or LCD/NCD excerpt with criteria highlighted Please contact [CONTACT NAME] at [PHONE] or [EMAIL] with any questions. Sincerely, [NAME], [TITLE] [PRACTICE NAME]
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