| Nurse practitioner | 5,219 |
| Physician assistant | 2,488 |
| Internal medicine | 1,943 |
| Family practice | 1,616 |
| Physical therapist (private practice) | 1,500 |
| Certified Registered Nurse Anesthetist (CRNA) | 959 |
| Emergency medicine | 876 |
| Anesthesiologist Assistant | 773 |
| Anesthesiology | 669 |
| Mass Immunization Roster Billers | 662 |
| Chiropractic | 647 |
| Obstetrics/gynecology | 641 |
| Optometrist | 587 |
| Diagnostic Radiology | 517 |
| Licensed clinical social worker | 489 |
| General surgery | 467 |
| Hospitalist | 453 |
| Mental Health Counselors | 443 |
| Orthopedic surgery | 423 |
| Cardiology | 371 |
| Psychiatry | 356 |
| Neurology | 304 |
| Centralized Flu | 304 |
| Ophthalmology | 296 |
| Occupational therapist (private practice) | 291 |
| Gastroenterology | 282 |
| Clinical psychologist | 258 |
| Ambulatory Surgical Center | 236 |
| Podiatry | 226 |
| Pulmonary disease | 213 |
| Nephrology | 213 |
| Dermatology | 212 |
| Pathology | 202 |
| Urology | 199 |
| Otolaryngology | 196 |
| Ambulance Service Supplier, e.g., private ambulance companies, funeral homes | 175 |
| Physical medicine and rehabilitation | 164 |
| Hematology/oncology | 160 |
| Audiologist (billing independently) | 159 |
| Critical care (intensivists) | 152 |
| Endocrinology | 120 |
| Infectious disease | 117 |
| Radiation oncology | 102 |
| Speech / language pathology | 97 |
| Vascular surgery | 97 |
| Interventional Cardiology | 94 |
| Rheumatology | 92 |
| Neurosurgery | 90 |
| Plastic and reconstructive surgery | 84 |
| Pediatric medicine | 83 |
| Pharmacy | 81 |
| Pain Management | 67 |
| Certified nurse midwife | 67 |
| General practice | 59 |
| Registered Dietician/Nutrition Professional | 54 |
| Medical oncology | 54 |
| Marriage and Family Therapist | 52 |
| Allergy/immunology | 51 |
| Clinical Laboratory (Billing Independently) | 49 |
| Thoracic surgery | 46 |
| Hospice and Palliative Care | 45 |
| Independent Diagnostic Testing Facility (IDTF) | 42 |
| Cardiac Electrophysiology | 39 |
| Interventional radiology | 38 |
| Hand surgery | 36 |
| Colorectal surgery (formerly proctology) | 33 |
| Interventional Pain Management (IPM) | 30 |
| Sports Medicine | 30 |
| Public Health or Welfare Agencies (Federal, State, and local) | 29 |
| Opioid Treatment Program | 28 |
| Surgical oncology | 24 |
| Hematology | 24 |
| Oral surgery (dentists only) | 23 |
| Certified clinical nurse specialist | 20 |
| Maxillofacial surgery | 19 |
| Nuclear medicine | 19 |
| Gynecologist/oncologist | 19 |
| Advanced Heart Failure and Transplant Cardiology | 18 |
| Psychologist (billing independently) | 17 |
| Geriatric medicine | 15 |
| Cardiac surgery | 15 |
| Sleep Medicine | 12 |
| Micrographic Dermatologic Surgery | 9 |
| Preventive medicine | 9 |
| Undersea and Hyperbaric Medicine | 8 |
| Unknown Provider | 7 |
| Medical Genetics and Genomics | 6 |
| Addiction medicine | 6 |
| Dentist | 4 |
| Home Infusion Therapy Services | 4 |
| All other suppliers, e.g., Drug Stores | 4 |
| General Psychiatry | 3 |
| Neuropsychiatry | 3 |
| Adult Congenital Heart Disease | 3 |
| Osteopathic manipulative therapy | 3 |
| Single or Multispecialty Clinic or Group Practice | 3 |
| Hematopoietic Cell Transplantation and Cellular Therapy | 2 |
| Unknown physician specialty | 2 |
| Portable X-Ray Supplier (Billing Independently) | 2 |
| Epileptologists | 2 |
| Oral and Maxillofacial Pathology | 1 |