This care may be covered by another payer per coordination of benefits.
The payer believes another insurance plan should be billed first (or also). COB rules determine payer order. Until the primary payer processes the claim, the secondary payer will not pay.
What This Means in Practice
Bill the primary payer first. Once the primary EOB is received, submit to the secondary with the EOB attached. Update COB order in the patient record.
Common Root Causes
- →Patient has Medicare and commercial insurance — Medicare Secondary Payer (MSP) rules apply
- →Dependent child covered under both parents plans — Birthday Rule not applied
- →Claim submitted to secondary before primary payer adjudicated
- →COB information not updated in payer system after insurance change
Common Billing Mistakes
- ✗Not asking about secondary insurance at registration
- ✗Billing the secondary before the primary
- ✗Not including the primary payer EOB with the secondary claim
- ✗Not understanding Medicare Secondary Payer rules
Documentation Required
Considerations
Prior Authorization
Authorization must be obtained from the primary payer. The secondary payer will follow the primary determination.
Eligibility
Verify both primary and secondary coverage at every visit. Determine the correct payer order using COB rules.
Coordination of Benefits
CO-22 IS the COB denial. Bill the primary first, wait for the EOB, then bill the secondary with the EOB attached.
Timely Filing
The timely filing clock runs from the date of service, not the COB denial date. Resubmit to the correct payer promptly.
Appeal & Resolution Strategy
Appeal with the primary payer EOB showing adjudication. Request the secondary to process with the primary EOB attached.
Related CPT Scenarios
- ▸Any CPT code for patients with dual insurance coverage
ICD-10 Considerations
Not applicable.
Related Payer Policy Guidance
Medicare
Medicare follows MSP rules. Working-age patients with employer coverage: employer plan is primary.
Commercial
Commercial payers follow the Birthday Rule for dependents and MSP rules for Medicare patients.
Related Resources
Knowledge Center Articles
Academy Lessons
Disclaimer: Code definitions and payer policies change. Always verify current definitions against CMS, X12, and payer-specific guidance. This information is for educational purposes only.