There are two types of doctors who accept Original Medicare: those who accept assignment (participating providers) and those who don’t accept assignment (non-participating providers). Participating providers are doctors who take Medicare and agree to accept the Medicare-approved amount for a service as payment in full. Most of these providers will bill Medicare first, and then allow you to pay any difference between what Medicare approved and what Medicare paid.
Non-participating providers are doctors who take Medicare, but do not necessarily agree to accept the Medicare-approved amount for a service as payment in full. However, these doctors are only able to charge you 15 percent more than the Medicare-approved amount for a service. In many cases these doctors will require you to pay the entire bill up front. They will then submit the claim to Medicare and have Medicare reimburse you directly for the bill you paid.
In short the answer to this question is "yes", however, you are more likely be billed up front by a non-participating provider. This is one of the reasons we recommend using a participating provider whenever possible.
If you have coverage through a Medicare Advantage Plan, the above information does not apply to you. You will pay the coinsurance and/or copayments that your plan requires, and these will likely vary depending on whether or not they are a network provider. For more information on the difference between Original Medicare and Medicare Advantage Plans, please see the following information pages: Medicare Overview, Medicare Advantage.