New and established patient
Solely for the purposes of distinguishing between new and established patients, professional services are those face-to-face services rendered by a physician and reported by a specific CPT code(s).
A new patient defined - One who has not received any professional services from the physician, or another physician of the same specialty who belongs to the same group practice, within the past three years.
An established patient - One who has received professional services from the physician, or another physician of the same specialty who belongs to the same group practice, within the past three years.
In the instance where a physician is on call for or covering for another physician, the patient’s encounter will be classified as it would have been by the physician who is not available.
No distinction is made between new and established patients in the emergency department or for consultations. E&M services in the emergency department category may be reported for any new or established patient who presents for treatment in the emergency department. Consultations in the office or hospital setting may be billed for a new or established patient.
As of January 1, 2010, Medicare does not recognize the consultation codes (99241-99255). However, providers are to code for a consultation when that is the service provided. Epic will crosswalk the consultation code to an appropriate new or established patient visit.
Source
American Medical Association, Current Procedural Terminology (CPT) 2003, Evaluation and Management (E&M) Guidelines.