Question: One of our ED physicians went on maternity leave, and we hired a substitute to fill in for her. Yesterday, the substitute physician performed simple incision and drainage (I & D) on a carbuncle on a Medicare patients lower back. How do I code for this? Washington, D.C. Subscriber Answer: Medicare refers to this type of substitute physician as locum tenens; you might employ one if an ED physician takes an extended leave of absence. Remember to append modifier Q6 (Service furnished by a locum tenens physician) to any services the substitute physician provides to Medicare patients. For private payers, call and check to see if they observe the Q6 modifier policies differ depending on the insurer. For this claim, report 10060 (Incision and drainage of abscess [e.g., carbuncle, suppurative hidradenitis, cutaneous or subcutaneous abscess, cyst, furuncle, or paronychia]; simple or single]) for the I&D with modifier Q6 appended to show that you are billing for a locum tenens physician. If the record supports a separately identified E/M service, report that as well. Also: Remember these tips when billing for a locum tenens physician: " Keep a file of the services the locum tenens physician provides in the regular physicians stead. The Medicare carrier might request the information when you are using the Q6 modifier. " Use the name and national provider identifier (NPI) of the physician who is out on leave to bill the locum tenens physicians services to Medicare. " Remember that the limit for locum tenens physicians is 60 days, starting with the locum tenens first date of service.