Definition
Physician Assistant (PA)
A physician assistant (PA) is a licensed clinician trained in a graduate-level medical program who examines, diagnoses and treats patients and prescribes medications, working with physicians under rules that each state sets.
1 min readReviewed September 14, 2026
Also known as: Physician associate, PA-C, Certified physician assistant
Key facts
- Education
- Graduate PA program accredited by ARC-PA
- Certification
- PANCE exam from NCCPA; certified PAs use the PA-C credential
- Licensing
- State medical boards or PA boards; practice rules vary by state
- Medicare billing
- Part B at 85% of the physician fee schedule; direct payment since 2022
- Taxonomy code
- 363A00000X (Physician Assistant)
What is a physician assistant?
PAs train in the medical model as generalists. Their graduate programs combine classroom science with clinical rotations across primary care, surgery, emergency medicine and other fields. After passing the Physician Assistant National Certifying Examination (PANCE), a PA can use the PA-C credential and apply for a state license.
Because their training is general rather than tied to one patient population, PAs can move between specialties, which differs from the population-focused certification of nurse practitioners.
The American Academy of Physician Assistants voted in 2021 to adopt the title physician associate. The legal title depends on each state's law, and many statutes still use physician assistant.
How PA practice rules work
Each state defines how PAs relate to physicians, and the models differ:
Prescribing authority, including for controlled substances, also depends on state law, and PAs need a DEA registration to prescribe controlled substances.
- Supervision: a physician oversees the PA under a written agreement or practice-level arrangement.
- Collaboration: the PA practices with a physician relationship that is less formal than supervision, sometimes only for a set number of practice hours.
- Optimal team practice: a model promoted by the national PA association that removes the requirement for a relationship with a specific physician, adopted in varying forms by some states.
Why PA data matters
PAs deliver a large share of care in fields such as surgery, emergency medicine, dermatology, orthopedics and primary care. Beginning January 1, 2022, the Consolidated Appropriations Act, 2021 allowed PAs to receive Medicare payment directly instead of only through an employer.
PAs hold Type 1 NPIs and appear in Medicare utilization data, Part D prescriber files and, starting with 2021 data, Open Payments. Any targeting or workforce analysis built on prescribing or procedure volume should include them.