CARC 100 Active

CO-100: Payment Made to Patient/Insured

TL;DR

Contractual adjustment — review against your contract terms. The patient is not liable for this amount.

Action
Review & Decide
Who Pays
Provider
Appeal
No
Patient Impact
None
Disclaimer
This content is for informational purposes only and does not constitute professional billing advice. Always verify information against your payer contracts and current coding guidelines. Consult a certified billing specialist for specific claim issues.

What Does CO-100 Mean?

With CO (Contractual Obligation), the CARC 100 adjustment for payment made to patient/insured is a contractual reduction. The provider absorbs this amount per the payer contract or regulatory payment methodology. The patient is not responsible for the adjusted amount. Review the remittance to confirm the adjustment is consistent with your contract terms.

CARC 100 appears on a remittance when the payer applies an adjustment for payment made to patient/insured. Review the group code and any accompanying RARC codes to understand the full context of this adjustment.

Common scenarios that trigger this adjustment include: the provider did not accept assignment on the claim, so the payer sent the payment directly to the patient or insured per non-assigned billing rules; The patient submitted the claim to their insurance company for reimbursement, and the payer issued payment to the patient rather than the provider; The provider is out of network, and the payer's policy is to reimburse the member directly for out-of-network services rather than paying the provider. The group code paired with CARC 100 determines who bears the financial responsibility — OA indicates a coordination of benefits or other payer adjustment, CO places it on the provider as a contractual obligation, PR shifts it to the patient.

Common Causes

Cause Frequency
Provider expected to collect directly from patient Since payment was sent to the patient, the provider is expected to collect the allowed amount from the patient and write off any contractual adjustment Most Common

How to Resolve

  1. Review the adjustment against contract terms Compare the CO-100 adjustment with your payer contract to confirm the reduction is consistent with agreed terms or regulatory methodology.
  2. Verify the adjustment amount Confirm the dollar amount of the adjustment is calculated correctly based on the contracted rate and the service provided.
  3. Appeal if the adjustment is incorrect If the adjustment does not align with contract terms, file an appeal with contract documentation and supporting evidence.
  4. Process the contractual adjustment If the adjustment is correct per contract terms, process it accordingly in your billing system. This amount cannot be transferred to the patient.
Do Not Appeal This Code

Payment Made to Patient/Insured recorded under CO is a contractual obligation — the provider absorbs this amount per the payer agreement. Without an error in how the contract was applied, appeals don't apply. Review the accompanying RARC codes for context and accept the adjustment when the contract terms were applied correctly.

How to Prevent CO-100

Also Filed As

The same CARC 100 may appear with different Group Codes:

OA-100 PR-100

Related Denial Codes

CO-3 — Co-payment Amount CO-85 — Patient Interest Adjustment CO-101 — Predetermination: Anticipated Payment CO-105 — Tax Withholding Amount CO-106 — Patient Payment Option Not in Effect

Sources

  1. https://www.cms.gov/medicare/claims-appeals/organization-determinations
  2. https://www.aapc.com/resources/claim-adjustment-reason-code-carc
  3. https://www.mdclarity.com/denial-code/100
  4. Codes maintained by X12. Visit x12.org for official definitions.