CO-22 Denial Code: Another Payer May Be Responsible (Coordination of Benefits)
The CO-22 denial code means the payer believes this care may be covered by another payer under coordination of benefits (COB) - in other words, you billed them as primary but their records say someone else should pay first. The claim will not be considered until the correct primary payer processes it or the COB information is straightened out.
Common Causes
- The patient has other coverage (spouse's plan, employer plan, auto or workers' comp claim) that the billed payer's records show as primary
- Outdated COB information on file - the other coverage ended but the payer was never notified
- Medicare Secondary Payer (MSP) situations: working-aged coverage, accident liability, or workers' compensation that makes Medicare secondary
- The claim was sent to the secondary payer without the primary payer's remittance information attached
- Registration captured only one insurance when the patient actually holds two
How to Fix CO-22
- Verify the patient's full coverage picture - ask the patient and run eligibility on all known plans to establish the correct primary/secondary order
- If another payer is primary, bill that payer first, then submit to this payer as secondary with the primary remittance advice attached
- If the other coverage has ended, have the patient contact the payer to update their COB records - payers usually require the update to come from the member
- For Medicare MSP denials, confirm whether the service is accident- or work-related and correct the MSP questionnaire responses
- After the COB record is corrected, resubmit the claim; note the timely filing clock, and document your original submission date
Frequently Asked Questions
CO-22 means the payer's records show another insurance may be responsible for this care under coordination of benefits. Either another payer is actually primary, or the payer's COB file is outdated and needs correcting before the claim can be processed.
Determine the true primary payer through eligibility checks and patient outreach. Bill the primary first and resubmit to this payer as secondary with the primary EOB. If the other coverage terminated, the patient typically must update COB with the payer directly before you resubmit.
No. It is a sequencing problem, not a coverage denial. Once the correct primary payer adjudicates the claim - or the COB records are updated to show this payer is primary - the claim can be resubmitted and processed normally.
Related Denial Codes
Related Resources
Claim adjustment reason codes and remittance advice remark codes are standardized code sets maintained by X12. The explanations on this page are written in our own words for educational purposes, based on public CMS and Medicare contractor documentation. Payer policies vary - always confirm handling with the specific payer's guidance and your contracts.