Common Medical Billing Denial Codes & Solutions
Every denial arrives with a claim adjustment reason code (CARC) that tells you exactly why the payer said no. Learn the most common medical billing denial codes, what they mean, and the specific action that resolves each one.
Payers communicate denials through CARC (Claim Adjustment Reason Codes) and RARC (Remittance Advice Remark Codes) on the ERA/EOB. Reading them correctly is the difference between a fast recovery and a permanent write-off. Here are the denial codes practices see most — and how to fix each.
The most common denial codes
| Code | Meaning | Fix |
|---|---|---|
| CO-45 | Charge exceeds the fee schedule / contracted amount | Contractual write-off — but verify the allowed amount is correct; appeal if underpaid vs your contract. |
| CO-97 | Service is bundled / included in another paid service | Check NCCI edits; append a modifier (e.g., 59/XU) only if the service was truly separate and documented. |
| PR-1 | Deductible amount (patient responsibility) | Bill the patient; verify the deductible was current at eligibility check. |
| PR-2 / PR-3 | Coinsurance / copay (patient responsibility) | Transfer balance to patient; collect at time of service next visit. |
| CO-16 | Claim lacks information / has a submission error | Read the paired RARC for the missing field; correct and resubmit before timely-filing expires. |
| CO-22 | Coordination of benefits — another payer is primary | Bill the correct primary payer first, then submit secondary with the primary EOB. |
| CO-29 | Timely-filing limit expired | Usually final — appeal only with proof of timely submission. Prevent with submission tracking. |
| CO-197 | Precertification / authorization absent | Obtain retro-auth if the payer allows; otherwise appeal. Prevent with front-end prior auth. |
| CO-11 | Diagnosis inconsistent with the procedure | Recheck ICD-10 to CPT linkage and medical necessity; correct coding and resubmit. |
| CO-18 | Duplicate claim / service | Confirm it is not a true duplicate; if a distinct service, append the appropriate modifier. |
Preventable vs. non-preventable
Most denials fall into two buckets. Front-end preventable (CO-16, CO-197, CO-22, PR-1) come from eligibility, authorization, and registration — fix them before the visit with eligibility verification. Coding-related (CO-97, CO-11, CO-18) come from bundling, medical necessity, and modifiers — fix them with certified coding and scrubbing.
The workflow that resolves denials fast
- Read the CARC + RARC together — the RARC often names the exact missing element.
- Route the denial by reason code to the right fix, not to a generic queue.
- Correct and resubmit (or appeal) before the timely-filing window closes.
- Fix the upstream cause so the same denial doesn't repeat next month.
This is exactly what our denial management service does — and prevention is why our clients' denial rates fall over time. Want your denial mix analyzed? Get a free revenue analysis.
FAQs
What is the difference between CARC and RARC?
A CARC (Claim Adjustment Reason Code, e.g. CO-45) states the general reason for the adjustment or denial; a RARC (Remittance Advice Remark Code) adds specific detail, such as which field was missing. Read them together to know the exact fix.
What does denial code CO-45 mean?
CO-45 means the charge exceeds the fee schedule or your contracted amount — normally a contractual write-off. But always verify the payer's allowed amount matches your contract; if they underpaid, appeal it.
How do I prevent the most denials?
Most preventable denials are front-end: verify eligibility and obtain prior authorization before the visit, and ensure clean registration data. That eliminates the largest categories (CO-16, CO-197, CO-22).