| Nurse practitioner | 4,025 |
| Physician assistant | 2,099 |
| Physical therapist (private practice) | 1,502 |
| Internal medicine | 1,381 |
| Family practice | 1,165 |
| Emergency medicine | 779 |
| Anesthesiology | 724 |
| Certified Registered Nurse Anesthetist (CRNA) | 624 |
| Diagnostic Radiology | 569 |
| Chiropractic | 507 |
| Optometrist | 463 |
| Licensed clinical social worker | 372 |
| Obstetrics/gynecology | 341 |
| Orthopedic surgery | 336 |
| General surgery | 331 |
| Mental Health Counselors | 297 |
| Mass Immunization Roster Billers | 295 |
| Cardiology | 284 |
| Podiatry | 272 |
| Psychiatry | 271 |
| Hospitalist | 258 |
| Clinical psychologist | 239 |
| Neurology | 235 |
| Dermatology | 208 |
| Occupational therapist (private practice) | 197 |
| Gastroenterology | 194 |
| Ophthalmology | 192 |
| Nephrology | 172 |
| Pathology | 147 |
| Ambulatory Surgical Center | 142 |
| Hematology/oncology | 139 |
| Centralized Flu | 139 |
| Pulmonary disease | 118 |
| Audiologist (billing independently) | 118 |
| Otolaryngology | 117 |
| Critical care (intensivists) | 116 |
| Urology | 114 |
| Registered Dietician/Nutrition Professional | 113 |
| Interventional Cardiology | 102 |
| Physical medicine and rehabilitation | 99 |
| Speech / language pathology | 97 |
| Certified nurse midwife | 85 |
| Pediatric medicine | 82 |
| Endocrinology | 81 |
| Radiation oncology | 80 |
| Neurosurgery | 78 |
| Infectious disease | 77 |
| Ambulance Service Supplier, e.g., private ambulance companies, funeral homes | 72 |
| Rheumatology | 54 |
| Pain Management | 50 |
| Vascular surgery | 50 |
| Clinical Laboratory (Billing Independently) | 50 |
| Plastic and reconstructive surgery | 49 |
| Allergy/immunology | 43 |
| General practice | 42 |
| Medical oncology | 41 |
| Cardiac Electrophysiology | 36 |
| Pharmacy | 34 |
| Marriage and Family Therapist | 31 |
| Hospice and Palliative Care | 29 |
| Colorectal surgery (formerly proctology) | 29 |
| Interventional radiology | 28 |
| Thoracic surgery | 26 |
| Hand surgery | 25 |
| Independent Diagnostic Testing Facility (IDTF) | 24 |
| Opioid Treatment Program | 24 |
| Surgical oncology | 22 |
| Cardiac surgery | 22 |
| Interventional Pain Management (IPM) | 20 |
| Sports Medicine | 19 |
| Geriatric medicine | 19 |
| Oral surgery (dentists only) | 18 |
| Sleep Medicine | 16 |
| Gynecologist/oncologist | 14 |
| Maxillofacial surgery | 10 |
| Osteopathic manipulative therapy | 10 |
| Portable X-Ray Supplier (Billing Independently) | 9 |
| Epileptologists | 9 |
| Micrographic Dermatologic Surgery | 8 |
| Dentist | 8 |
| Unknown physician specialty | 8 |
| Nuclear medicine | 7 |
| Preventive medicine | 5 |
| Medical Genetics and Genomics | 5 |
| Hematology | 5 |
| Certified clinical nurse specialist | 4 |
| Psychologist (billing independently) | 3 |
| Hematopoietic Cell Transplantation and Cellular Therapy | 3 |
| Intensive Cardiac Rehabilitation | 2 |
| Unknown Provider | 2 |
| Advanced Heart Failure and Transplant Cardiology | 2 |
| Neuropsychiatry | 2 |
| Medicare Diabetes Preventive Program | 2 |
| Addiction medicine | 2 |
| Undersea and Hyperbaric Medicine | 2 |
| Home Infusion Therapy Services | 1 |
| Medical Toxicology | 1 |
| Public Health or Welfare Agencies (Federal, State, and local) | 1 |
| Single or Multispecialty Clinic or Group Practice | 1 |
| All other suppliers, e.g., Drug Stores | 1 |
| Orofacial Pain | 1 |