CMS has provided additional guidance on a provision of the November 19, 2008 final Medicare physician fee schedule rule for calendar year 2009. In the final rule, CMS adopted a requirement that an entity providing mobile diagnostic testing services enroll with Medicare as an Independent Diagnostic Testing Facility (IDTF), comply with the IDTF performance standards, and bill Medicare directly for its services (although CMS did not require a mobile testing entity to bill directly for its services they are furnished “under arrangement” to hospitals). In a frequently-asked question dated December 15, 2008, CMS clarifies that if the mobile provider of testing services provides only the equipment and the non-physician technicians, they are not required to enroll and bill as an IDTF. Note, however, that if the mobile provider also provides the physician supervision of the test as well as the equipment and the technician, the mobile entity would be required to enroll and bill as an IDTF effective January 1, 2009.