| Nurse practitioner | 1,706 |
| Internal medicine | 524 |
| Physician assistant | 518 |
| Family practice | 454 |
| Certified Registered Nurse Anesthetist (CRNA) | 413 |
| Physical therapist (private practice) | 334 |
| Licensed clinical social worker | 276 |
| Anesthesiology | 244 |
| Emergency medicine | 241 |
| Obstetrics/gynecology | 226 |
| Optometrist | 190 |
| Mental Health Counselors | 186 |
| Diagnostic Radiology | 178 |
| Mass Immunization Roster Billers | 150 |
| Clinical psychologist | 148 |
| Psychiatry | 144 |
| Hospitalist | 134 |
| Chiropractic | 132 |
| Orthopedic surgery | 116 |
| Pediatric medicine | 113 |
| Cardiology | 113 |
| Neurology | 110 |
| General surgery | 100 |
| Ambulance Service Supplier, e.g., private ambulance companies, funeral homes | 98 |
| Ophthalmology | 90 |
| Gastroenterology | 89 |
| Hematology/oncology | 76 |
| Pulmonary disease | 74 |
| Podiatry | 72 |
| Audiologist (billing independently) | 70 |
| Occupational therapist (private practice) | 68 |
| Dermatology | 66 |
| Nephrology | 64 |
| Pathology | 61 |
| Otolaryngology | 53 |
| Anesthesiologist Assistant | 52 |
| Centralized Flu | 50 |
| Physical medicine and rehabilitation | 49 |
| Urology | 47 |
| Endocrinology | 46 |
| Speech / language pathology | 43 |
| Infectious disease | 41 |
| Critical care (intensivists) | 40 |
| Neurosurgery | 30 |
| Radiation oncology | 30 |
| Registered Dietician/Nutrition Professional | 30 |
| Ambulatory Surgical Center | 27 |
| Interventional Cardiology | 25 |
| Rheumatology | 25 |
| Cardiac Electrophysiology | 25 |
| Thoracic surgery | 23 |
| Vascular surgery | 23 |
| Certified nurse midwife | 22 |
| Plastic and reconstructive surgery | 21 |
| Certified clinical nurse specialist | 20 |
| Allergy/immunology | 17 |
| Hand surgery | 17 |
| Pain Management | 16 |
| Advanced Heart Failure and Transplant Cardiology | 14 |
| General practice | 13 |
| Pharmacy | 12 |
| Geriatric medicine | 11 |
| Clinical Laboratory (Billing Independently) | 11 |
| Opioid Treatment Program | 11 |
| Gynecologist/oncologist | 11 |
| Medical oncology | 11 |
| Interventional radiology | 11 |
| Independent Diagnostic Testing Facility (IDTF) | 10 |
| Surgical oncology | 10 |
| Sports Medicine | 9 |
| Sleep Medicine | 9 |
| Epileptologists | 9 |
| Hematology | 8 |
| Colorectal surgery (formerly proctology) | 8 |
| Cardiac surgery | 6 |
| Hospice and Palliative Care | 6 |
| Oral surgery (dentists only) | 5 |
| Interventional Pain Management (IPM) | 5 |
| Marriage and Family Therapist | 5 |
| Single or Multispecialty Clinic or Group Practice | 4 |
| Addiction medicine | 4 |
| Micrographic Dermatologic Surgery | 4 |
| Maxillofacial surgery | 3 |
| Preventive medicine | 2 |
| General Psychiatry | 2 |
| Unknown physician specialty | 2 |
| Public Health or Welfare Agencies (Federal, State, and local) | 1 |
| Hematopoietic Cell Transplantation and Cellular Therapy | 1 |
| Nuclear medicine | 1 |
| Home Infusion Therapy Services | 1 |
| Portable X-Ray Supplier (Billing Independently) | 1 |
| Dentist | 1 |
| Neuropsychiatry | 1 |
| Peripheral vascular disease | 1 |