Is Medicare Always Primary? What Coordination of Benefits Rules Mean for Your Coverage

Is Medicare Always Primary?

Medicare is not always the primary payer. Whether it pays first depends on what other insurance you have, your age, disability status, and the type of coverage involved. The general rule is that Medicare pays after any primary insurance, and before you are responsible for remaining costs — but the order changes depending on the situation.

When Medicare Is Primary

Medicare becomes the primary payer when no other insurance is responsible for a claim. This typically applies when:

• You are enrolled only in Medicare with no employer or retiree coverage.
• Your employer has fewer than 20 employees, making Medicare the primary plan.
• You have End-Stage Renal Disease and have been on Medicare for more than 30 months.
• You have Medicaid, which generally acts as secondary coverage and does not push Medicare back.

When Medicare Is Secondary

Other insurance pays first and Medicare pays what remains, up to its allowed amount. Common scenarios include:

• Current employer or union coverage when the employer has 20 or more employees.
• Veterans Affairs (VA) benefits, which are primary for VA-authorized care.
• Active-duty military TRICARE, which is primary for covered services.
• Workers' compensation for injuries or illnesses covered by a claim.
• No-fault or liability insurance, such as an auto or liability settlement.

Coordination of Benefits and Claim Processing

Coordination of benefits prevents duplicate payments and ensures claims are paid in the correct order. The primary payer processes the claim first and sends an Explanation of Benefits. Medicare then receives that information and pays its portion as secondary. You may still owe deductibles, coinsurance, or copayments that neither plan covers, depending on the services and your specific coverage.

How to Confirm Your Payer Order

If you are unsure which plan is primary, check with each insurer or contact Medicare at 1-800-MEDICARE. Your employer's benefits office can confirm whether your group plan is primary or secondary based on its size and your employment status. Keeping your insurers informed of all your coverage helps claims process correctly and reduces unexpected bills.