| Nurse practitioner | 3,482 |
| Internal medicine | 3,068 |
| Physical therapist (private practice) | 2,567 |
| Physician assistant | 2,508 |
| Licensed clinical social worker | 1,531 |
| Anesthesiology | 1,253 |
| Emergency medicine | 1,181 |
| Psychiatry | 1,055 |
| Family practice | 955 |
| Obstetrics/gynecology | 894 |
| Diagnostic Radiology | 828 |
| Clinical psychologist | 708 |
| Cardiology | 697 |
| Podiatry | 598 |
| Neurology | 582 |
| Gastroenterology | 533 |
| Ophthalmology | 532 |
| Occupational therapist (private practice) | 525 |
| Optometrist | 522 |
| Certified Registered Nurse Anesthetist (CRNA) | 505 |
| Hospitalist | 482 |
| General surgery | 454 |
| Orthopedic surgery | 401 |
| Dermatology | 392 |
| Mass Immunization Roster Billers | 389 |
| Pathology | 358 |
| Physical medicine and rehabilitation | 323 |
| Mental Health Counselors | 315 |
| Pulmonary disease | 285 |
| Chiropractic | 277 |
| Nephrology | 273 |
| Otolaryngology | 264 |
| Urology | 262 |
| Infectious disease | 261 |
| Endocrinology | 257 |
| Medical oncology | 242 |
| Pediatric medicine | 224 |
| Speech / language pathology | 191 |
| Hematology/oncology | 191 |
| Audiologist (billing independently) | 171 |
| Critical care (intensivists) | 165 |
| Rheumatology | 143 |
| Centralized Flu | 135 |
| Neurosurgery | 127 |
| Plastic and reconstructive surgery | 115 |
| Radiation oncology | 113 |
| Pharmacy | 107 |
| Vascular surgery | 105 |
| Registered Dietician/Nutrition Professional | 99 |
| Allergy/immunology | 96 |
| Certified nurse midwife | 91 |
| General practice | 82 |
| Interventional radiology | 79 |
| Geriatric medicine | 76 |
| Interventional Cardiology | 74 |
| Pain Management | 70 |
| Hospice and Palliative Care | 66 |
| Cardiac Electrophysiology | 58 |
| Ambulance Service Supplier, e.g., private ambulance companies, funeral homes | 57 |
| Thoracic surgery | 52 |
| Ambulatory Surgical Center | 46 |
| Sports Medicine | 44 |
| Colorectal surgery (formerly proctology) | 43 |
| Hematology | 42 |
| Clinical Laboratory (Billing Independently) | 40 |
| Advanced Heart Failure and Transplant Cardiology | 40 |
| Surgical oncology | 36 |
| Gynecologist/oncologist | 35 |
| Cardiac surgery | 34 |
| Oral surgery (dentists only) | 27 |
| Independent Diagnostic Testing Facility (IDTF) | 26 |
| Nuclear medicine | 25 |
| Hand surgery | 25 |
| Interventional Pain Management (IPM) | 21 |
| Opioid Treatment Program | 20 |
| Marriage and Family Therapist | 18 |
| Osteopathic manipulative therapy | 17 |
| Sleep Medicine | 16 |
| Maxillofacial surgery | 15 |
| Neuropsychiatry | 12 |
| Micrographic Dermatologic Surgery | 7 |
| Preventive medicine | 6 |
| Medical Genetics and Genomics | 6 |
| Hematopoietic Cell Transplantation and Cellular Therapy | 6 |
| Unknown physician specialty | 5 |
| Dentist | 5 |
| Certified clinical nurse specialist | 5 |
| Single or Multispecialty Clinic or Group Practice | 4 |
| Adult Congenital Heart Disease | 4 |
| Portable X-Ray Supplier (Billing Independently) | 3 |
| Medical Toxicology | 3 |
| Oral and Maxillofacial Pathology | 3 |
| Addiction medicine | 3 |
| General Psychiatry | 3 |
| Home Infusion Therapy Services | 3 |
| Epileptologists | 2 |
| Undersea and Hyperbaric Medicine | 1 |
| Psychologist (billing independently) | 1 |
| All other suppliers, e.g., Drug Stores | 1 |