How does Medicare work with my current insurance?
Coordination of Benefits
When you have Medicare and other insurance, one pays first (primary) and the other pays second (secondary). The primary payer pays its share, then the secondary may cover some or all of the remaining costs.
If you have employer coverage from a current job at a company with 20 or more employees, your employer plan usually pays first, and Medicare pays second. If you're retired or work for a small employer (fewer than 20 employees), Medicare generally pays first.
- Medicare is primary for most retirees with retiree coverage
- Employer plan is primary if you're still working and the employer has 20+ employees
- Medicare is primary if you have COBRA or a small employer plan
- Medicaid pays after Medicare for those who qualify
- TRICARE and VA benefits have special rules
Types of Coverage and Enrollment
If you have a Medicare Advantage Plan (Part C), it replaces Original Medicare and may include prescription drug coverage. You generally can't use both Original Medicare and a Medicare Advantage Plan together.
If you have a Medigap policy, it supplements Original Medicare and helps pay deductibles, coinsurance, and copayments. You can't have Medigap with a Medicare Advantage Plan. Enroll in Medicare during your Initial Enrollment Period to avoid penalties.
What to Do
Contact your current insurance company and Medicare to confirm which pays first. Ask your HR department if you have employer coverage. You may need to sign up for Medicare even if you have other insurance to avoid gaps.
If you have questions, call 1-800-MEDICARE or visit medicare.gov. A State Health Insurance Assistance Program (SHIP) counselor can provide free, unbiased help.
Common mistakes
- Assuming your employer coverage is enough—Medicare may still be primary or you may face penalties for late enrollment.
- Thinking you can have both Medicare Advantage and Medigap—you can't; you must choose one.
- Not telling your providers about all your coverage—this can cause billing errors and delays.
