Question: Can I bill 99211 for a physician assistant (PA) acting as a supervising physician for a Protime Clinic within a practice? Michigan Subscriber Answer: APA does not meet the definition of a physician, and therefore cannot function as a supervisory physician under the diagnostic test benefit. The PAcan perform the test, but she cannot supervise anyone. Generally, you should not bill incident-to when a PA supervises the nonphysician practitioner.