According to CMS “Incident to a physician’s professional services means that the services or supplies are furnished as an integral, although incidental, part of the physician’s personal professional services in the course of diagnosis or treatment of an injury or illness”
Incident to services are performed by personnel who are NOT physicians, but are paid for performing physicians services. This group of professionals: “Auxiliary Personnel” includes any individual who is acting under the supervision of a physician.When describing “any individual”, CMS deliberately chose the term to define auxiliary personnel “So that the physician (or other practitioner), under his or her discretion and license, may use the service of anyone ranging from another physician to a medical assistant.” Furthermore, “...impossible to exhaustively list all incident-to services and those specific auxiliary personnel who may perform each service.”
(Federal Register/Vol. 66, No. 212/ Thursday November 1, 2001, pgs 55267 – 55268)