| Nurse practitioner | 2,497 |
| Physician assistant | 1,072 |
| Internal medicine | 1,037 |
| Family practice | 686 |
| Certified Registered Nurse Anesthetist (CRNA) | 592 |
| Emergency medicine | 481 |
| Physical therapist (private practice) | 356 |
| Diagnostic Radiology | 352 |
| Obstetrics/gynecology | 277 |
| General practice | 267 |
| Anesthesiology | 254 |
| Mental Health Counselors | 248 |
| Optometrist | 229 |
| Licensed clinical social worker | 227 |
| Chiropractic | 225 |
| Centralized Flu | 214 |
| Cardiology | 199 |
| General surgery | 152 |
| Podiatry | 149 |
| Gastroenterology | 149 |
| Psychiatry | 148 |
| Mass Immunization Roster Billers | 147 |
| Orthopedic surgery | 141 |
| Neurology | 139 |
| Clinical psychologist | 139 |
| Ophthalmology | 118 |
| Pulmonary disease | 94 |
| Occupational therapist (private practice) | 92 |
| Hospitalist | 91 |
| Urology | 89 |
| Anesthesiologist Assistant | 86 |
| Dermatology | 79 |
| Critical care (intensivists) | 79 |
| Infectious disease | 75 |
| Hematology/oncology | 69 |
| Interventional Cardiology | 68 |
| Physical medicine and rehabilitation | 68 |
| Nephrology | 68 |
| Ambulatory Surgical Center | 66 |
| Pathology | 58 |
| Otolaryngology | 57 |
| Endocrinology | 56 |
| Speech / language pathology | 53 |
| Audiologist (billing independently) | 50 |
| Radiation oncology | 47 |
| Pediatric medicine | 47 |
| Rheumatology | 39 |
| Neurosurgery | 38 |
| Marriage and Family Therapist | 37 |
| Vascular surgery | 35 |
| Plastic and reconstructive surgery | 33 |
| Cardiac Electrophysiology | 32 |
| Thoracic surgery | 31 |
| Colorectal surgery (formerly proctology) | 30 |
| Certified nurse midwife | 27 |
| Ambulance Service Supplier, e.g., private ambulance companies, funeral homes | 25 |
| Pain Management | 25 |
| Hand surgery | 24 |
| Interventional Pain Management (IPM) | 24 |
| Medical oncology | 23 |
| Sports Medicine | 17 |
| Hospice and Palliative Care | 17 |
| Independent Diagnostic Testing Facility (IDTF) | 16 |
| Registered Dietician/Nutrition Professional | 16 |
| Allergy/immunology | 16 |
| Clinical Laboratory (Billing Independently) | 15 |
| Osteopathic manipulative therapy | 14 |
| Pharmacy | 12 |
| Geriatric medicine | 11 |
| Interventional radiology | 10 |
| Gynecologist/oncologist | 10 |
| Advanced Heart Failure and Transplant Cardiology | 9 |
| Cardiac surgery | 7 |
| Opioid Treatment Program | 7 |
| Surgical oncology | 6 |
| Medical Genetics and Genomics | 5 |
| Hematology | 4 |
| Sleep Medicine | 4 |
| Psychologist (billing independently) | 4 |
| Home Infusion Therapy Services | 3 |
| Oral surgery (dentists only) | 3 |
| Maxillofacial surgery | 3 |
| Nuclear medicine | 3 |
| Certified clinical nurse specialist | 3 |
| Undersea and Hyperbaric Medicine | 2 |
| Micrographic Dermatologic Surgery | 2 |
| Neuropsychiatry | 1 |
| Hematopoietic Cell Transplantation and Cellular Therapy | 1 |
| Unknown physician specialty | 1 |
| Peripheral vascular disease | 1 |
| Oral Medicine | 1 |
| Medicare Diabetes Preventive Program | 1 |