Does Medicare Advantage change the coordination of benefits rules?

No. If you have Medicare Advantage, the same coordination of benefits rules apply. Your Medicare Advantage plan acts in place of Original Medicare and coordinates with other coverage using the same primary/secondary framework.

If Medicare is secondary, do I still need to enroll in Part B?

Yes, in most cases. Even if Medicare is secondary, you need to be enrolled in Part B for it to pay as a secondary payer. Failing to enroll in Part B can leave you with uncovered costs.

How does Medigap work with coordination of benefits?

Medigap always pays after Original Medicare. Medicare pays first as primary, then Medigap covers some or all of the remaining cost-sharing (deductibles, coinsurance, copayments) depending on your plan.

Does Medicare Advantage change the coordination of benefits rules?

No. If you have Medicare Advantage, the same coordination of benefits rules apply. Your Medicare Advantage plan acts in place of Original Medicare and coordinates with other coverage using the same primary/secondary framework.

If Medicare is secondary, do I still need to enroll in Part B?

Yes, in most cases. Even if Medicare is secondary, you need to be enrolled in Part B for it to pay as a secondary payer. Failing to enroll in Part B can leave you with uncovered costs.

How does Medigap work with coordination of benefits?

Medigap always pays after Original Medicare. Medicare pays first as primary, then Medigap covers some or all of the remaining cost-sharing (deductibles, coinsurance, copayments) depending on your plan.

When Is Medicare Primary vs. Secondary? (2026 Guide)

When you have Medicare and another form of health insurance, coordination of benefits rules determine which plan pays first (primary) and which pays second (secondary). The primary payer processes the claim first and pays its share. The secondary payer then covers some or all of the remaining balance.

Medicare Primary vs. Secondary: Quick Reference

When Medicare Is Primary or Secondary (2026)

Your Situation	Medicare Pays	Other Insurance Pays
Medicare is your only coverage	Primary	N/A
You have employer coverage, employer has 20+ employees, you are actively working	Secondary	Primary
You have employer coverage, employer has fewer than 20 employees	Primary	Secondary
You are retired with retiree insurance	Primary	Secondary
You have COBRA	Primary	Secondary
You have a Medigap (Medicare Supplement) plan	Primary	Secondary (Medigap fills gaps)
You have Medicaid	Primary	Secondary (Medicaid pays last)
You have VA benefits	Each pays separately for its own services	Each pays separately
You have workers' compensation for a work-related injury	Secondary	Primary (workers' comp pays first)
You have TRICARE (military retiree)	Primary	Secondary

Employer Size Matters for Active Workers

If you are still working and your employer has 20 or more employees, your employer plan is primary and Medicare is secondary. If your employer has fewer than 20 employees, Medicare is primary. Enrolling in Part B is especially important in the smaller-employer scenario, as your employer plan may pay very little without Medicare as the primary payer.

What Happens If a Claim Is Filed Out of Order?

If a claim is submitted to the secondary payer first, it will typically be denied or returned with a request for the primary payer's explanation of benefits (EOB). Always submit claims to the primary payer first. If you are unsure which plan is primary, call the Benefits Coordination and Recovery Center (BCRC) at 1-855-798-2627.

When Is Medicare Primary vs. Secondary?

Medicare Primary vs. Secondary: Quick Reference

What Happens If a Claim Is Filed Out of Order?

Need Help Understanding Your Medicare Options?

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