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Coordination of Benefits

If you have more than one health insurance plan, insurance companies use a Coordination of Benefits (COB) form to figure out who pays for your claims. The COB also helps to make sure that the insurance companies don’t both pay for the same medical services or pay more than the total cost of your care. This helps keep costs down.

Each insurance company has their own COB rules. And those rules may be different. This means it’s very important that you call your insurance company to make sure your COB is up to date. Many insurance companies will not pay a medical claim unless they have a current COB on file. If your COB is not correct, you may have to pay the bill.

How does the COB work?

When you have more than one insurance plan, one is usually your primary plan, and the other is a secondary plan. The COB rules say the primary plan pays its share of the bill first. Then the secondary plan pays the rest, within its coverage limits.

Even if you have secondary insurance, you may still have to pay your:

  • deductibles
  • copayments
  • coinsurance. 

What if I have Medicare?

If you have Medicare and other health insurance, they’ll use a COB form just like private insurance. To update your COB with Medicare, or if you have questions about how it works, call the Benefits Coordination and Recovery Center at (855) 798-2627. TTY users can call (855) 797-2627.

You’ll need to tell them if your health or drug coverage changes. You’ll also need to give them:

  • your name 
  • the name and address of your other insurance plan 
  • your policy number 
  • the date your other insurance was added, changed, or stopped, and why that happened.

If your Medicare plan changes, make sure you tell your other insurance plan, employer, or union benefits person.

To learn more about how Medicare does a COB with other insurance, download this PDF. Or visit: