| Nurse practitioner | 3,362 |
| Physical therapist (private practice) | 1,893 |
| Physician assistant | 1,711 |
| Internal medicine | 1,653 |
| Family practice | 1,329 |
| Licensed clinical social worker | 1,113 |
| Anesthesiology | 801 |
| Emergency medicine | 751 |
| Clinical psychologist | 682 |
| Certified Registered Nurse Anesthetist (CRNA) | 610 |
| Chiropractic | 584 |
| Obstetrics/gynecology | 566 |
| Optometrist | 532 |
| Hospitalist | 529 |
| Mental Health Counselors | 525 |
| Diagnostic Radiology | 497 |
| Psychiatry | 451 |
| Neurology | 362 |
| Podiatry | 350 |
| Orthopedic surgery | 300 |
| Ophthalmology | 295 |
| Occupational therapist (private practice) | 294 |
| General surgery | 289 |
| Cardiology | 288 |
| Gastroenterology | 288 |
| Pathology | 240 |
| Hematology/oncology | 236 |
| Dermatology | 215 |
| Pulmonary disease | 205 |
| Centralized Flu | 203 |
| Nephrology | 202 |
| Mass Immunization Roster Billers | 202 |
| Physical medicine and rehabilitation | 172 |
| Urology | 153 |
| Otolaryngology | 153 |
| Audiologist (billing independently) | 141 |
| Infectious disease | 138 |
| Ambulance Service Supplier, e.g., private ambulance companies, funeral homes | 124 |
| Endocrinology | 121 |
| Speech / language pathology | 119 |
| Pediatric medicine | 115 |
| Rheumatology | 102 |
| Registered Dietician/Nutrition Professional | 99 |
| Interventional Cardiology | 91 |
| Clinical Laboratory (Billing Independently) | 86 |
| Critical care (intensivists) | 79 |
| Neurosurgery | 75 |
| Radiation oncology | 70 |
| Plastic and reconstructive surgery | 66 |
| Allergy/immunology | 64 |
| Vascular surgery | 64 |
| Certified nurse midwife | 61 |
| Ambulatory Surgical Center | 55 |
| Cardiac Electrophysiology | 54 |
| Independent Diagnostic Testing Facility (IDTF) | 44 |
| Geriatric medicine | 44 |
| Interventional radiology | 44 |
| General practice | 42 |
| Thoracic surgery | 42 |
| Hand surgery | 34 |
| Certified clinical nurse specialist | 33 |
| Sports Medicine | 32 |
| Medical oncology | 30 |
| Hospice and Palliative Care | 29 |
| Advanced Heart Failure and Transplant Cardiology | 29 |
| Pain Management | 29 |
| Surgical oncology | 28 |
| Colorectal surgery (formerly proctology) | 28 |
| Sleep Medicine | 28 |
| Marriage and Family Therapist | 24 |
| Interventional Pain Management (IPM) | 23 |
| Opioid Treatment Program | 23 |
| Gynecologist/oncologist | 20 |
| Cardiac surgery | 19 |
| Maxillofacial surgery | 16 |
| Pharmacy | 13 |
| Neuropsychiatry | 12 |
| Oral surgery (dentists only) | 11 |
| Hematopoietic Cell Transplantation and Cellular Therapy | 10 |
| Dentist | 9 |
| Hematology | 8 |
| Portable X-Ray Supplier (Billing Independently) | 8 |
| Preventive medicine | 7 |
| Micrographic Dermatologic Surgery | 6 |
| Epileptologists | 6 |
| All other suppliers, e.g., Drug Stores | 4 |
| Addiction medicine | 4 |
| Single or Multispecialty Clinic or Group Practice | 4 |
| Nuclear medicine | 3 |
| Osteopathic manipulative therapy | 3 |
| Medical Genetics and Genomics | 3 |
| Adult Congenital Heart Disease | 3 |
| Peripheral vascular disease | 1 |
| Slide Preparation Facilities | 1 |
| Undersea and Hyperbaric Medicine | 1 |
| Prosthodontics | 1 |
| Medicare Diabetes Preventive Program | 1 |
| Unknown physician specialty | 1 |
| Home Infusion Therapy Services | 1 |