| Nurse practitioner | 3,258 |
| Physician assistant | 2,357 |
| Physical therapist (private practice) | 2,139 |
| Family practice | 2,086 |
| Internal medicine | 1,255 |
| Chiropractic | 855 |
| Emergency medicine | 849 |
| Anesthesiology | 805 |
| Optometrist | 642 |
| Licensed clinical social worker | 608 |
| Mental Health Counselors | 572 |
| Certified Registered Nurse Anesthetist (CRNA) | 533 |
| Hospitalist | 513 |
| Diagnostic Radiology | 504 |
| Obstetrics/gynecology | 427 |
| Clinical psychologist | 406 |
| Orthopedic surgery | 340 |
| General surgery | 339 |
| Psychiatry | 325 |
| Mass Immunization Roster Billers | 282 |
| Ophthalmology | 281 |
| Neurology | 259 |
| Occupational therapist (private practice) | 255 |
| Gastroenterology | 232 |
| Cardiology | 226 |
| Dermatology | 209 |
| Podiatry | 199 |
| Pathology | 180 |
| Hematology/oncology | 177 |
| Pediatric medicine | 168 |
| Pulmonary disease | 168 |
| Urology | 161 |
| Physical medicine and rehabilitation | 156 |
| Audiologist (billing independently) | 146 |
| Otolaryngology | 142 |
| Ambulance Service Supplier, e.g., private ambulance companies, funeral homes | 138 |
| Nephrology | 124 |
| Certified nurse midwife | 114 |
| Infectious disease | 113 |
| Registered Dietician/Nutrition Professional | 104 |
| Ambulatory Surgical Center | 100 |
| Centralized Flu | 97 |
| Radiation oncology | 91 |
| Interventional Cardiology | 87 |
| Marriage and Family Therapist | 84 |
| Rheumatology | 81 |
| Endocrinology | 81 |
| Neurosurgery | 77 |
| Critical care (intensivists) | 73 |
| Speech / language pathology | 63 |
| Medical oncology | 60 |
| Plastic and reconstructive surgery | 55 |
| Vascular surgery | 52 |
| Allergy/immunology | 46 |
| Pharmacy | 45 |
| General practice | 42 |
| Sports Medicine | 41 |
| Clinical Laboratory (Billing Independently) | 40 |
| Cardiac Electrophysiology | 40 |
| Hospice and Palliative Care | 38 |
| Hand surgery | 36 |
| Pain Management | 34 |
| Sleep Medicine | 34 |
| Interventional radiology | 33 |
| Thoracic surgery | 30 |
| Geriatric medicine | 26 |
| Independent Diagnostic Testing Facility (IDTF) | 22 |
| Colorectal surgery (formerly proctology) | 19 |
| Cardiac surgery | 18 |
| Interventional Pain Management (IPM) | 17 |
| Gynecologist/oncologist | 17 |
| Advanced Heart Failure and Transplant Cardiology | 16 |
| Hematology | 16 |
| Oral surgery (dentists only) | 15 |
| Surgical oncology | 15 |
| Opioid Treatment Program | 14 |
| Medical Genetics and Genomics | 12 |
| Unknown physician specialty | 12 |
| Nuclear medicine | 12 |
| Epileptologists | 11 |
| Osteopathic manipulative therapy | 11 |
| Preventive medicine | 9 |
| Addiction medicine | 9 |
| Psychologist (billing independently) | 8 |
| Adult Congenital Heart Disease | 7 |
| Unknown Provider | 7 |
| Micrographic Dermatologic Surgery | 7 |
| Dentist | 6 |
| Home Infusion Therapy Services | 5 |
| General Psychiatry | 5 |
| Maxillofacial surgery | 4 |
| Neuropsychiatry | 3 |
| Portable X-Ray Supplier (Billing Independently) | 3 |
| Certified clinical nurse specialist | 2 |
| Medicare Diabetes Preventive Program | 2 |
| Undersea and Hyperbaric Medicine | 2 |
| Oral Medicine | 1 |
| Oral and Maxillofacial Pathology | 1 |
| Public Health or Welfare Agencies (Federal, State, and local) | 1 |
| Radiation Therapy Centers | 1 |
| Orofacial Pain | 1 |