42 CFR §489.32

1. (a)Services requested by beneficiary. If services furnished at the request of a beneficiary (or his or her representative) are more expensive than, or in excess of, services covered under Medicare—
   1. (1)A provider may charge the beneficiary an amount that does not exceed the difference between—
      1. (i)The provider's customary charges for the services furnished; and
      2. (ii)The provider's customary charges for the kinds and amounts of services that are covered under Medicare.
   2. (2)A provider may not charge for the services unless they have been requested by the beneficiary (or his or her representative) nor require a beneficiary to request services as a condition of admission.
   3. (3)To avoid misunderstanding and disputes, a provider must inform any beneficiary who requests a service for which a charge will be made that there will be a specified charge for that service.
2. (b)Services not requested by the beneficiary. For special provisions that apply when a provider customarily furnishes more expensive services, see § 413.35 of this chapter.