| Nurse practitioner | 629 |
| Physician assistant | 537 |
| Physical therapist (private practice) | 255 |
| Family practice | 215 |
| Anesthesiology | 188 |
| Internal medicine | 174 |
| Licensed clinical social worker | 170 |
| Emergency medicine | 161 |
| Diagnostic Radiology | 125 |
| Hospitalist | 78 |
| Mass Immunization Roster Billers | 73 |
| Obstetrics/gynecology | 72 |
| Psychiatry | 72 |
| Neurology | 67 |
| Optometrist | 65 |
| Orthopedic surgery | 65 |
| Chiropractic | 61 |
| Pathology | 61 |
| Ophthalmology | 55 |
| Certified Registered Nurse Anesthetist (CRNA) | 55 |
| Mental Health Counselors | 54 |
| General surgery | 54 |
| Clinical psychologist | 53 |
| Dermatology | 48 |
| Gastroenterology | 45 |
| Cardiology | 44 |
| Podiatry | 41 |
| Certified nurse midwife | 41 |
| Physical medicine and rehabilitation | 41 |
| Hematology/oncology | 40 |
| Pulmonary disease | 36 |
| Pediatric medicine | 36 |
| Occupational therapist (private practice) | 31 |
| Otolaryngology | 31 |
| Audiologist (billing independently) | 23 |
| Nephrology | 23 |
| Infectious disease | 23 |
| Medical oncology | 22 |
| Urology | 20 |
| Plastic and reconstructive surgery | 16 |
| Neurosurgery | 16 |
| Centralized Flu | 16 |
| Pain Management | 16 |
| Critical care (intensivists) | 16 |
| Ambulatory Surgical Center | 15 |
| Marriage and Family Therapist | 15 |
| Speech / language pathology | 14 |
| Rheumatology | 14 |
| Sports Medicine | 13 |
| Endocrinology | 13 |
| Radiation oncology | 13 |
| Registered Dietician/Nutrition Professional | 10 |
| Vascular surgery | 9 |
| Allergy/immunology | 9 |
| Interventional Cardiology | 8 |
| Interventional radiology | 7 |
| Hospice and Palliative Care | 7 |
| Ambulance Service Supplier, e.g., private ambulance companies, funeral homes | 7 |
| Neuropsychiatry | 7 |
| Clinical Laboratory (Billing Independently) | 7 |
| Geriatric medicine | 7 |
| Colorectal surgery (formerly proctology) | 7 |
| Thoracic surgery | 7 |
| Hematology | 5 |
| Independent Diagnostic Testing Facility (IDTF) | 5 |
| Surgical oncology | 5 |
| Hand surgery | 5 |
| Sleep Medicine | 4 |
| Pharmacy | 4 |
| Oral surgery (dentists only) | 4 |
| Cardiac Electrophysiology | 3 |
| Anesthesiologist Assistant | 3 |
| Cardiac surgery | 3 |
| Opioid Treatment Program | 3 |
| General practice | 3 |
| Nuclear medicine | 2 |
| Interventional Pain Management (IPM) | 2 |
| Public Health or Welfare Agencies (Federal, State, and local) | 1 |
| Mammography Screening Center | 1 |
| Unknown physician specialty | 1 |
| Unknown Provider | 1 |
| Medical Genetics and Genomics | 1 |
| Addiction medicine | 1 |
| Gynecologist/oncologist | 1 |
| Undersea and Hyperbaric Medicine | 1 |
| Epileptologists | 1 |
| Osteopathic manipulative therapy | 1 |
| Advanced Heart Failure and Transplant Cardiology | 1 |
| Oral and Maxillofacial Pathology | 1 |