Free · No sign-up · No patient data needed
What does this denial code mean?
Type the code from your remittance. Get the plain-English meaning, the fix, and how long you have to appeal with each payer.
Codes only. Don't paste names, dates of birth or member IDs.
Most-searched codes
- 16Claim is missing information or has billing errors
- 18Exact duplicate of a claim already processed
- 22Another payer may be primary
- 27Service was after coverage ended
- 29Filing deadline passed
- 45Charge is above the allowed amount
- 50Payer says the service wasn't medically necessary
- 96Charge isn't covered
- 97Paid as part of another service (bundled)
- 150Information doesn't support the level of service billed
- 197Prior authorization missing
- 204Not covered by the patient's current plan
CO, PR, OA, PI: what the prefix means
| Prefix | Means | Bill the patient? (Medicare) |
|---|---|---|
| CO | Contractual obligation. The provider absorbs the amount. Under Medicare, the patient cannot be billed for it. | No |
| PR | Patient responsibility. The patient owes the amount and it may be billed to the patient. | Yes |
| OA | Other adjustment. An adjustment that assigns no financial liability to either the provider or the patient. | No |
| PI | Payer-initiated reduction. A payer-initiated reduction. X12 allows it, but Medicare has never used it because it doesn't say who is financially liable. | Depends |
Sources: X12 Claim Adjustment Group Codes, checked 2026-10-04; CMS Transmittal 470 (CR 3685, Feb 2005): group and reason code use, checked 2026-10-04
Appeal letters ready to send
Four fill-in-the-blank appeal letters (E/M downcode, coverage or medical necessity, prior auth on file, proof of timely filing) plus a one-page payer deadline sheet.