Medical Denial Code Guide
Look up CARC and RARC denial codes. Find causes, resolutions, and prevention tips.
How Denial Codes Work
Example — Claim denied for missing procedure code (CO-16 + M51)
CO
Group Code
who pays
-
16
CARC
why denied
+
M51
RARC
what exactly
Group Code
Tells you who pays. CO = provider absorbs. PR = patient owes. Same CARC means different things per group.
CARC
Claim Adjustment Reason Code — tells you why a claim was denied or adjusted. ~280 active codes.
RARC
Remittance Advice Remark Code — supplements the CARC with exactly what's wrong. Always check the RARC before fixing a claim.
Browse by Group Code
CO
Contractual Obligation
Provider bears the cost. Cannot bill patient. Most common group code.
PR
Patient Responsibility
Patient owes. Deductibles, copays, coinsurance, non-covered services.
OA
Other Adjustment
Adjustments that don't fit CO or PR. Often coordination of benefits.
PI
Payor Initiated Reduction
Payer-driven reduction. Similar to CO but with different appeal rights.
Most Common Denial Codes
| Code | Name | Action | |
|---|---|---|---|
| CO-16 | Missing Information or Billing Error | Verify & Resubmit | → |
| CO-45 | Charge Exceeds Fee Schedule / Maximum Allowable | Review & Decide | → |
| PR-1 | Deductible Amount | Collect from Patient | → |
| CO-4 | Procedure Code / Modifier Mismatch | Resubmit | → |
| CO-97 | Bundled Service — Not Paid Separately | Review & Decide | → |