Question: Our neurologist performed a level-three E/M service on a new patient last week. The visit lasted 45 minutes, yet CPT estimates the physician would spend only 30 minutes of face-to-face time with the patient for a level-three new patient E/M service. Can I append modifier -21 to the E/M code to account for the extra time? Answer: No, you cannot append modifier -21 (Prolonged evaluation and management service) to a level-three E/M service.
Mississippi Subscriber
In this case, you should report only 99203 (Office or other outpatient visit for the evaluation and management of a new patient, which requires these three key components: a detailed history; a detailed examination; medical decision making of low complexity) for the E/M.
You should use modifier -21 only for "the highest level of evaluation and management service," according to CPT - meaning that you can only use it in conjunction with 99205 for a new patient outpatient visit.