| Nurse practitioner | 8,484 |
| Physician assistant | 2,960 |
| Internal medicine | 2,331 |
| Family practice | 2,276 |
| Certified Registered Nurse Anesthetist (CRNA) | 1,796 |
| Physical therapist (private practice) | 1,313 |
| Emergency medicine | 1,309 |
| Licensed clinical social worker | 1,245 |
| Mental Health Counselors | 1,037 |
| Anesthesiology | 982 |
| Optometrist | 914 |
| Diagnostic Radiology | 891 |
| Chiropractic | 869 |
| Obstetrics/gynecology | 834 |
| Mass Immunization Roster Billers | 788 |
| Clinical psychologist | 615 |
| General surgery | 579 |
| Orthopedic surgery | 576 |
| Ambulance Service Supplier, e.g., private ambulance companies, funeral homes | 570 |
| Psychiatry | 549 |
| Cardiology | 538 |
| Hospitalist | 497 |
| Podiatry | 487 |
| Neurology | 460 |
| Ophthalmology | 393 |
| Gastroenterology | 387 |
| Pathology | 378 |
| Pulmonary disease | 360 |
| Pediatric medicine | 308 |
| Dermatology | 278 |
| Hematology/oncology | 265 |
| Anesthesiologist Assistant | 264 |
| Audiologist (billing independently) | 263 |
| Occupational therapist (private practice) | 259 |
| Urology | 252 |
| Nephrology | 238 |
| Otolaryngology | 236 |
| Physical medicine and rehabilitation | 226 |
| Infectious disease | 159 |
| Endocrinology | 157 |
| Certified nurse midwife | 157 |
| Speech / language pathology | 152 |
| Critical care (intensivists) | 151 |
| Centralized Flu | 145 |
| Certified clinical nurse specialist | 145 |
| Neurosurgery | 143 |
| Radiation oncology | 143 |
| Rheumatology | 132 |
| Plastic and reconstructive surgery | 131 |
| Registered Dietician/Nutrition Professional | 124 |
| Ambulatory Surgical Center | 123 |
| Interventional Cardiology | 114 |
| Vascular surgery | 112 |
| Allergy/immunology | 92 |
| Medical oncology | 89 |
| Cardiac Electrophysiology | 84 |
| Pain Management | 78 |
| Sports Medicine | 71 |
| Thoracic surgery | 66 |
| Pharmacy | 62 |
| Hospice and Palliative Care | 60 |
| General practice | 58 |
| Hematology | 50 |
| Colorectal surgery (formerly proctology) | 48 |
| Sleep Medicine | 45 |
| Hand surgery | 42 |
| Interventional radiology | 41 |
| Geriatric medicine | 40 |
| Cardiac surgery | 37 |
| Opioid Treatment Program | 35 |
| Gynecologist/oncologist | 34 |
| Advanced Heart Failure and Transplant Cardiology | 33 |
| Independent Diagnostic Testing Facility (IDTF) | 30 |
| Surgical oncology | 30 |
| Clinical Laboratory (Billing Independently) | 27 |
| Addiction medicine | 26 |
| Interventional Pain Management (IPM) | 24 |
| Maxillofacial surgery | 21 |
| Single or Multispecialty Clinic or Group Practice | 19 |
| Oral surgery (dentists only) | 16 |
| Marriage and Family Therapist | 16 |
| Osteopathic manipulative therapy | 14 |
| Public Health or Welfare Agencies (Federal, State, and local) | 12 |
| Preventive medicine | 12 |
| Micrographic Dermatologic Surgery | 11 |
| Nuclear medicine | 10 |
| Medical Genetics and Genomics | 9 |
| Dentist | 6 |
| Epileptologists | 6 |
| Peripheral vascular disease | 6 |
| Unknown Provider | 5 |
| Hematopoietic Cell Transplantation and Cellular Therapy | 4 |
| Adult Congenital Heart Disease | 3 |
| Unknown physician specialty | 3 |
| Portable X-Ray Supplier (Billing Independently) | 3 |
| Neuropsychiatry | 3 |
| Home Infusion Therapy Services | 3 |
| Medicare Diabetes Preventive Program | 3 |
| Prosthodontics | 2 |
| Oral and Maxillofacial Pathology | 1 |
| Psychologist (billing independently) | 1 |
| Undersea and Hyperbaric Medicine | 1 |
| General Psychiatry | 1 |
| Radiation Therapy Centers | 1 |