CO-3: Co-payment Amount

What Does CO-3 Mean?

CO-3 designates the copay amount as a contractual write-off that the provider must absorb. This is uncommon for copay adjustments but can occur when the provider's contract with the payer prohibits copay collection for certain services or patient populations, or when the payer incorrectly assigned the copay to CO instead of PR.

CARC 3 on a remittance signals that the payer applied the patient's contractual copayment to the claim. A copay is a fixed dollar amount — not a percentage — that the patient owes for a specific type of service (office visit, specialist visit, urgent care, emergency room). Unlike coinsurance, the copay does not fluctuate with the allowed amount; it is a flat fee determined by the patient's plan design.

This code appears overwhelmingly with Group Code PR, confirming the copay as a direct patient obligation. In a well-run revenue cycle, the copay should already have been collected at the front desk before the patient was seen. When PR-3 shows up on the ERA, it typically means the copay was either not collected at service, the collected amount was less than what the payer applied, or the practice waived collection and now needs to bill the patient after the fact.

One area that catches billing teams off guard is service-type copay tiers. Many plans assign different copays for primary care visits, specialist visits, and facility-based services. If the payer classifies the encounter differently than you expected — for example, treating an E/M visit as a specialist encounter instead of primary care — the copay amount on the ERA may be higher than what was collected. Similarly, some payers waive copays for ACA-mandated preventive services. If a preventive visit was miscoded as a diagnostic visit, the patient may be charged a copay they should not owe.

Common Causes

How to Resolve

Confirm the copay amount and service-type classification, reconcile against any amount already collected, then bill the patient for the remainder.

1. Review your payer contract terms Check whether your participation agreement includes clauses that waive copay collection for specific services or populations. If CO-3 matches your contract, the write-off is correct.
2. Verify the group code assignment CO-3 on a copay is unusual. Contact the payer to confirm this was not a processing error. If it should have been PR-3, request a corrected remittance so you can bill the patient.
3. Post the contractual adjustment If CO-3 is validated, write off the copay amount as a contractual allowance. Do not bill the patient.

Common RARC Pairings

The RARC code tells you exactly what triggered the CO-3:

How to Prevent CO-3

• Maintain a clear record of which payer contracts include copay waiver provisions so billing staff know when CO-3 is expected
• Audit remittances for CO-3 assignments that should have been PR-3, as incorrect group codes reduce collectible revenue
• Address recurring CO-3 copay write-offs during contract renegotiations if they are not aligned with your contractual intent

General Prevention

• Verify copay amounts during scheduling and at check-in using real-time eligibility verification, comparing the copay on the insurance card against the electronic benefits response
• Collect copays at the time of service before the patient is seen, using point-of-service collection policies and posted copay expectations
• Maintain an updated fee schedule that maps service types to their corresponding copay tiers (office visit, specialist, urgent care, ER) for each major payer
• Confirm whether preventive services are copay-exempt under the patient's plan before collecting to avoid overcharging
• Train front-desk staff on verifying copay amounts, distinguishing between in-network and out-of-network copay rates, and handling copay waivers
• Monitor remittances for copay adjustments and flag any discrepancies between expected and actual copay amounts applied by payers

Also Filed As

The same CARC 3 may appear with different Group Codes:

Related Denial Codes