Those enrolled in Original Medicare will receive a mailing showing Part A and Part B covered services every quarter. This Medicare Summary Notice (MSN) displays all services and supplies that providers and supplies billed to Medicare during that quarter. It shows what Medicare paid and the maximum amount you may owe the provider. Please note that the MSN is NOT a bill. If you have a plan that supplements Original Medicare, that plan may pay for all or a portion of the owed provider amount. If you are only enrolled in Original Medicare, the provider or supplier will directly bill you for the owed amount. It is good to review and keep a copy of your MSN in case you run into any billing issues with your provider or supplier. If you wish you order a replacement of your Medicare Summary Notice or change your address, please call Medicare at 1-800-MEDICARE (1-800-772-1213).
The below example found on medicare.gov shows what the Medicare Summary Notice looks like and how to read the provided information.