Does anyone know where I can find information to share with my doctors regarding billing for a new patient vs an established patient within the same group? EX: An Endocrinologist referred a patient to see an Internal Medicine physician within the same group with the same tax id. According to what I read in the guidelines in the CPT book we can bill as a new patient. But I need further documentation to support this to show a physician that is telling me I am incorrect. Any help would be appreciated. Thank you.