Every denied claim costs time twice: once to find out why it was denied, and again to fix and resubmit or appeal it. Some denials are unavoidable, but many trace back to a small number of preventable causes. This guide covers the denial reasons practices most often see, what they usually mean, and the habits that help prevent them.
Rejections vs. denials
A rejection happens before the payer processes the claim, usually because of missing or invalid data or formatting problems. Rejected claims are corrected and resubmitted. A denial means the payer processed the claim and refused payment for some or all of it. Denials may need a corrected claim, additional information, or a formal appeal. Because rejected claims never appear on a remittance, they need their own monitoring.
Common denial reasons and what they usually mean
Payers explain denials with Claim Adjustment Reason Codes (CARCs), often with Remittance Advice Remark Codes (RARCs) that add detail. A few that practices see frequently:
| Code | General meaning | Typical prevention |
|---|---|---|
| CARC 16 | Claim lacks information or has a submission or billing error | Charge review and claim scrubbing before submission; check the remark code for the specific missing item |
| CARC 18 | Exact duplicate claim or service | Check claim status before resubmitting; use corrected-claim procedures instead of sending a new original claim |
| CARC 22 | Care may be covered by another payer (coordination of benefits) | Confirm primary and secondary coverage at intake; ask patients to update COB with their plan |
| CARC 27 | Expenses incurred after coverage terminated | Verify eligibility before every visit, not only the first one |
| CARC 29 | Time limit for filing has expired | Track submission dates and payer filing limits; work rejections promptly |
| CARC 50 | Service not deemed medically necessary by the payer | Make sure documentation supports the service and diagnosis; check payer coverage policies |
| CARC 97 | Service is included in the payment for another service | Review bundling edits and modifier use with your coding resources |
| CARC 197 | Precertification, authorization, or notification absent | Flag services that need authorization during verification and track approvals |
Code descriptions here are simplified. The official code lists are maintained by X12 and updated regularly, and each payer applies them in its own way.
Prevention starts at the front desk
- Verify eligibility before every visit. Coverage changes more often than many practices expect, especially around the start of the year and plan open-enrollment periods.
- Capture complete demographic and insurance data. Name spelling, date of birth, and member ID must match the payer's records exactly.
- Confirm coordination of benefits. Ask patients about other coverage and record primary and secondary payers correctly.
- Identify authorization needs early. Check payer requirements when the service is scheduled, not after it is performed.
Prevention continues after the visit
- Review charges before submission. Look for missing modifiers, invalid code combinations, and diagnosis–procedure mismatches, and route clinical questions to your coding resources.
- Work rejections daily. A quick correction keeps a rejected claim well inside the filing limit.
- Categorize every denial. Group denials by reason and payer. A short monthly review of the top reasons often shows which process change will prevent the most rework.
- Track appeal deadlines. Each payer sets its own appeal window. Missing it usually ends the conversation.
When to get help
If denials are being written off because no one has time to work them, or the same reasons keep appearing month after month, it may be time for a structured denial management process. Our denial management and appeals support works individual denials and reports the patterns behind them, and our eligibility verification service focuses on preventing front-end denials.