Question: One of our physicians is going on vacation next month, and we are hiring a substitute physician. Can you tell me about locum tenens (LT) billing, and how we should use the concept to bill for our substitute? Maine Subscriber Answer: Simply put, when you bill for the substitute physician's services with Medicare - or payers who follow Medicare's billing guidelines- you'll want to use LT billing principles. Short answer: An LT physician must be substituting for another physician, according to Jill Young, CPC, CEDC, CIMC, owner of Young Medical Consulting in East Lansing, Michigan. In other words, you can't hire an LT as "extra help" if your practice experiences a temporary surge in business. There are three rules you must remember when you are billing for an LT physician: 1. Medicare ID billing number: Bill the LT's services with the ID number of the physician he's subbing for. Example: Your practice hires an LT physician to fill in for Dr. X. The LT physician performs a level-two E/M service for an established patient. On the claim, you should report 99212 (Office or other outpatient visit for the evaluation and management of an established patient, which requires at least 2 of these 3 key components: a problem focused history; a problem focused examination; straightforward medical decision making ...) for the LT's services under Dr. X's Medicare ID number. 2. Modifiers: Remember to append modifier 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) to 99212 in the above example. In fact, append Q6 whenever you code for a service that an LT physician provides. 3. Time limit: Medicare does place limits on the amount of time you can bill under LT rules. An LT can fill in for 60 continuous days starting with his first date of service, Young explains. Example: Dr. Y goes on leave, and you hire an LT physician to fill in for Dr. Y. The LT performs his first service for a patient on Sept. 1. In this example, the LT physician can bill under Dr. Y's Medicare ID until Oct. 30; 60 days after the Sept. 1 service.