DME denial codes, explained
The claim-adjustment reason codes (CARCs) DME billing teams actually see — in plain language, with the fix path and appeal odds for each.
Group prefixes on your remit: CO = contractual obligation (provider write-off unless corrected/appealed),
PR = patient responsibility, OA = other adjustment, PI = payer-initiated.
The same numeric code can appear under different groups depending on liability.
| Code | What it means |
|---|---|
| PR-1 | Applied to the patient’s deductible |
| PR-2 | Coinsurance |
| PR-3 | Copayment |
| CO-4 | Modifier missing or inconsistent with the procedure |
| CO-5 | Procedure inconsistent with place of service |
| CO-9 | Diagnosis inconsistent with patient age |
| CO-11 | Diagnosis inconsistent with the procedure |
| CO-15 | Authorization number missing or invalid |
| CO-16 | Claim lacks information or has a submission error |
| CO-18 | Exact duplicate claim or service |
| CO-22 | Another payer may be responsible (coordination of benefits) |
| OA-23 | Prior payer’s adjudication impact |
| CO-26 | Expenses incurred before coverage began |
| CO-27 | Expenses incurred after coverage ended |
| CO-29 | Filed past the timely-filing limit |
| PR-31 | Patient cannot be identified as insured |
| CO-45 | Charge exceeds the fee schedule / allowed amount |
| CO-50 | Not deemed medically necessary |
| CO-55 | Experimental / investigational |
| CO-58 | Treatment location inappropriate for the service |
| CO-96 | Non-covered charge |
| CO-97 | Bundled — included in another adjudicated service |
| CO-109 | Wrong payer / contractor for this claim |
| CO-110 | Billing date predates service date |
| CO-119 | Benefit maximum reached |
| CO-140 | Patient ID and name don’t match |
| CO-146 | Diagnosis invalid for the date of service |
| CO-150 | Documentation doesn’t support this level of service |
| CO-151 | Frequency / quantity not supported |
| CO-167 | Diagnosis not covered |
| CO-170 | Payment denied for this provider type |
| CO-176 | Prescription not current |
| CO-177 | Patient hasn’t met eligibility requirements |
| CO-181 | Procedure code invalid on the date of service |
| CO-182 | Modifier invalid on the date of service |
| CO-183 | Referring provider not eligible to refer |
| CO-184 | Ordering provider not eligible to order/prescribe |
| CO-185 | Rendering provider not eligible to perform |
| CO-189 | Unlisted code billed when a specific code exists |
| CO-197 | Prior authorization absent |
| CO-198 | Authorization exceeded |
| CO-204 | Not covered under the patient’s current benefit plan |
| CO-206 | NPI missing |
| CO-226 | Requested records not received from provider |
| CO-236 | Procedure combination not allowed together |
| CO-242 | Out-of-network provider |
| CO-252 | Attachment / documentation required |
| CO-253 | Sequestration reduction |
| CO-272 | Coverage / program guidelines not met |
| CO-273 | Coverage guidelines exceeded |
| CO-B7 | Provider not certified/eligible on this date |
Denials are a workflow, not a mystery
MyMedi-AI tracks every denial, maps it to the fix, and drafts appeal letters with the right documentation checklist for DME claims.
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