How Medicare works with other insurance
If you have Medicare and other health insurance or coverage, each type of coverage is called a "payer." When there's more than one payer, "coordination of benefits" rules decide which one pays first. The "primary payer" pays what it owes on your bills first, and then sends the rest to the "secondary payer" to pay. In some 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 uncovered costs.
If your employer insurance is the secondary payer, you may need to enroll in Medicare Part B before your insurance will pay.
Paying "first" means paying the whole bill up to the limits of the coverage. It doesn't always mean the primary payer pays first in time. 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.
* Note Tell your doctor and other health care providers if you have coverage in addition to Medicare. This will help them send your bills to the correct payer to avoid delays.
What's a conditional payment?
A conditional payment is a payment Medicare makes for services another payer may be responsible for. Medicare makes this conditional payment so you won't have to use your own money to pay the bill. The payment is "conditional" because it must be repaid to Medicare when a settlement, judgment, award, or other payment is made.
If Medicare makes a conditional payment for an item or service, and you get a settlement, judgment, award, or other payment for that item or service from an insurance company later, the conditional payment must be repaid to Medicare. You’re responsible for making sure Medicare gets repaid for the conditional payment.