Question: One of our physicians, Dr. Adams, is going on a cruise this summer. Dr. Adams has decided to bring in a locum tenens (LT) physician, Dr. Carr, to cover for him in his absence. We've heard there is an important modifier we must append to the LT's services. Can you tell us more about this modifier? Hawaii Subscriber Answer: The modifier you are thinking of is Q6 (Service furnished under a fee-for-time compensation arrangement by a substitute physician; or by a substitute physical therapist furnishing outpatient physical therapy services in a health professional shortage area, a medically underserved area, or a rural area), and you must append this modifier to any code for services the locum provides. When you bill the LT physician's services, you bill them under the physician he is replacing for that time period. Modifier Q6 tells the payer that the LT physician is practicing medicine on behalf of the original physician, who is not available to see patients. This also indicates that the situation is temporary. The modifier protects your physician in the event of an audit because your original physician, Dr. Adams, didn't perform those services - the locum, Dr. Carr, did.