If the doctor, other health care supplier, or provider, doesn't agree to accept assignment,
they may charge you more than the Medicare-approved Amount
; however, for most services, there is a limit to what they can charge you. The highest amount you can be charged is called the "limiting charge." The limiting charge is 15% over the Medicare-approved amount (but may be lower in your state). The limiting charge applies only to certain services and doesn't apply to supplies and other durable medical equipment. In addition, you might have to pay the entire charge at the time of service. Medicare will send you payment for its share of the charge when the claim is processed.
To get more information about assignment, visit www.medicare.gov on the web and select "Search Tools" at the top of the page. Then select "Find a Doctor." You can also call 1-800-MEDICARE (1-800-633-4227).