Skip to main content

CO-228 Denial Code: Info Not Supplied to Prior Payer

CO-228 means the claim was denied because this provider, another provider, or the subscriber did not supply information a previous payer requested for its adjudication. The fix usually starts with the primary payer, not the payer that sent this code.

Quick facts

Code
CO-228 (CARC 228)
Status
Active In use since September 21, 2008.
Code set
Claim Adjustment Reason Codes (CARC)
Group codes
  • CO (Contractual Obligation): The payer holds the provider responsible until the prior payer's adjudication is complete. The amount generally should not be billed to the patient at this stage.
  • PR (Patient Responsibility): Sometimes used when the subscriber was the one who failed to respond to the prior payer.
Official description
Denied for failure of this provider, another provider or the subscriber to supply requested information to a previous payer for their adjudication
X12 Claim Adjustment Reason Codes, retrieved September 25, 2026
Last verified
against the official X12 list.

What CO-228 means

CARC 228 says the claim is denied for failure of this provider, another provider, or the subscriber to supply requested information to a previous payer for their adjudication. It is a secondary (or tertiary) payer’s way of saying: the primary payer never finished, because it was waiting on information, so we can’t finish either.

The information gap might be yours, another provider’s, or the subscriber’s. For example, the primary may have sent the member a COB questionnaire that was never returned, or asked a different provider for records. The secondary payer looks at the primary’s EOB, sees a denial for missing information, and returns CO-228.

Common causes

  • Primary payer denied for missing records (its own CARC 226), and the claim was forwarded to secondary anyway.
  • Member did not answer the primary payer’s questionnaire (its CARC 227).
  • Another provider’s documentation was needed by the primary, for example the ordering physician’s records.
  • Claim crossed over automatically from the primary to the secondary before the primary’s request was resolved.

How to fix it

  1. Pull the primary payer’s EOB or ERA and find its denial reason and remark codes.
  2. Identify who owed information to the primary: your practice, another provider, or the subscriber.
  3. Resolve it with the primary. Send your records, ask the other provider to send theirs, or have the patient contact the primary payer.
  4. Wait for the primary’s new adjudication, then resubmit to the secondary with the updated primary payment data (loops 2320/2430 on the 837, or the new EOB on paper).
  5. Watch timely filing for both payers. Secondary deadlines often run from the primary’s EOB date, but rules vary by payer.
  6. Hold patient billing until both payers have finished.

How to prevent it

  • Don’t forward claims to the secondary until the primary has actually paid or issued a final denial.
  • Monitor primary payer requests and respond before they turn into denials; see CO-226.
  • Remind patients to answer insurer questionnaires from all their plans.
  • Keep a COB workflow that checks the primary EOB’s status before secondary submission. Eligibility and COB denials covers this in more detail.

Remark codes that may appear with CO-228

  • N36 (Claim must meet primary payer's processing requirements before we can consider payment.): The claim must meet the primary payer's processing requirements before this payer will consider it.
  • MA04 (Secondary payment cannot be considered without the identity of or payment information from the primary payer.): The primary payer's payment information is missing or was not reported.
  • N479 (Missing Explanation of Benefits (Coordination of Benefits or Medicare Secondary Payer).): The prior payer's explanation of benefits is missing.
  • CO-226 (Information requested from the Billing/Rendering Provider was not provided or not provided timely or was insufficient/incomplete.): Information was requested by this payer from the provider, not by a previous payer.
  • CO-227 (Information requested from the patient/insured/responsible party was not provided or was insufficient/incomplete.): Information was requested by this payer from the patient.
  • OA-23 (The impact of prior payer(s) adjudication including payments and/or adjustments. (Use only with Group Code OA)): Reports the prior payer's payments and adjustments on a secondary claim.
  • OA-22 (This care may be covered by another payer per coordination of benefits.): The care may be covered by another payer under coordination of benefits.

CO-228 FAQ

Who do I contact about CO-228?

Start with the primary or prior payer. Find out what it requested and from whom, get the information to it, and let it complete adjudication. Then resubmit to the secondary payer with the updated primary EOB.

Why is the secondary payer denying for the primary payer's request?

Secondary payers base their payment on how the primary processed the claim. If the primary denied or pended the claim for missing information, the secondary generally will not pay until that is resolved.

Can I bill the patient for CO-228?

Not while it is under the CO group. If the subscriber was the one who did not respond, remind them to contact the primary payer before considering patient billing.

Does CO-228 restart the secondary payer's filing deadline?

Not automatically. Many secondary payers measure timely filing from the primary payer's final EOB date, but rules differ. Confirm the secondary payer's rule so the resubmission is not denied as late.