CO-22 denial: Other payer primary
The payer believes another insurer should pay first under coordination of benefits.
Common causes
- The patient has more than one plan and the order on file is wrong
- The patient's other coverage changed and was not updated
- Medicare is secondary to an employer plan and the claim went to Medicare first
How to fix it
- Verify all active coverage and the correct order of payers
- Update the registration and send the claim to the primary payer first
- Bill the secondary payer with the primary payer's remittance attached
How to prevent it
- Ask every patient about other coverage at each visit
- Run an eligibility check that returns coordination of benefits data
Zenith billers and AR specialists work denials like this inside your practice-management system, and your practice stays the billing provider. See AR follow-up and medical billing.
Educational summary, not billing or legal advice. Payer rules and deadlines vary; always check the payer’s own policy and the remark code on your remittance.