Medicare contracts with private insurance companies, called Medicare Administrative Contractors (MAC) to handle Medicare claims. This is why your Medicare Summary Notice (MSN) may have the name and address of a private insurance company on it. The MSN is a summary of claims for health care services Medicare processed for you during the previous three months. The MSN is not a bill.

You can call 800-Medicare for claim issues, questions about coverage, complaints, and denials. If Medicare denies payment for an item or service and you decide to appeal, the first level of appeal you make is to the Medicare Administrative Contractor (MAC). You can find out where to send your appeal by looking at your MSN. The name and address of the Medicare Administrative Counselor will be on your MSN.  

Different Medicare Administrative Contractors cover different regions of the country. A region may include many states, just one state or just part of a state. If you need help finding out who your MAC is you can call 800-MEDICARE (800-633-4227) to ask for your MAC’s contact information.