How Medicare works with other insurance

If you have Medicare and other health insurance (like from a group health plan, retiree coverage, or Medicaid), each type of coverage is called a “payer.” When there’s more than one payer, “coordination of benefits” rules decide who pays first. The “primary payer” pays what it owes on your bills first, and then sends the rest to the “secondary payer” (supplemental payer) to pay. In some rare cases, there may also be a third payer.

What it means to pay primary/secondary

• The insurance that pays first (primary payer) pays up to the limits of its coverage.
• The one that pays second (secondary payer) only pays if there are costs the primary insurer didn’t cover.
• The secondary payer (which may be Medicare) may not pay all the remaining costs.
• If your group health plan or retiree coverage is the secondary payer, you may need to enroll in Medicare Part B before they’ll pay.

If the insurance company doesn’t pay the 

claim promptly (usually within 120 days), your doctor or other provider may bill Medicare. Medicare may make a conditional payment to pay the bill, and then later recover any payments the primary payer should’ve made.