| Nurse practitioner | 5,163 |
| Physical therapist (private practice) | 2,927 |
| Physician assistant | 2,634 |
| Internal medicine | 2,505 |
| Family practice | 2,015 |
| Licensed clinical social worker | 1,711 |
| Anesthesiology | 1,255 |
| Emergency medicine | 1,187 |
| Clinical psychologist | 1,049 |
| Chiropractic | 919 |
| Certified Registered Nurse Anesthetist (CRNA) | 906 |
| Obstetrics/gynecology | 900 |
| Hospitalist | 848 |
| Mental Health Counselors | 816 |
| Optometrist | 811 |
| Diagnostic Radiology | 789 |
| Psychiatry | 701 |
| Podiatry | 542 |
| Neurology | 531 |
| Ophthalmology | 487 |
| Orthopedic surgery | 470 |
| Occupational therapist (private practice) | 468 |
| General surgery | 447 |
| Cardiology | 445 |
| Gastroenterology | 439 |
| Pathology | 380 |
| Dermatology | 339 |
| Hematology/oncology | 335 |
| Centralized Flu | 321 |
| Mass Immunization Roster Billers | 312 |
| Pulmonary disease | 311 |
| Nephrology | 291 |
| Physical medicine and rehabilitation | 280 |
| Otolaryngology | 238 |
| Urology | 224 |
| Infectious disease | 222 |
| Audiologist (billing independently) | 208 |
| Ambulance Service Supplier, e.g., private ambulance companies, funeral homes | 195 |
| Endocrinology | 193 |
| Pediatric medicine | 177 |
| Speech / language pathology | 171 |
| Rheumatology | 159 |
| Registered Dietician/Nutrition Professional | 152 |
| Interventional Cardiology | 134 |
| Critical care (intensivists) | 125 |
| Neurosurgery | 123 |
| Clinical Laboratory (Billing Independently) | 123 |
| Radiation oncology | 112 |
| Plastic and reconstructive surgery | 109 |
| Allergy/immunology | 103 |
| Certified nurse midwife | 93 |
| Cardiac Electrophysiology | 85 |
| Vascular surgery | 84 |
| Ambulatory Surgical Center | 80 |
| Independent Diagnostic Testing Facility (IDTF) | 73 |
| Certified clinical nurse specialist | 68 |
| Thoracic surgery | 67 |
| Interventional radiology | 66 |
| Geriatric medicine | 64 |
| General practice | 63 |
| Sports Medicine | 60 |
| Medical oncology | 55 |
| Hand surgery | 55 |
| Pain Management | 55 |
| Hospice and Palliative Care | 47 |
| Advanced Heart Failure and Transplant Cardiology | 46 |
| Surgical oncology | 43 |
| Marriage and Family Therapist | 42 |
| Colorectal surgery (formerly proctology) | 41 |
| Sleep Medicine | 40 |
| Opioid Treatment Program | 36 |
| Cardiac surgery | 34 |
| Interventional Pain Management (IPM) | 30 |
| Gynecologist/oncologist | 29 |
| Maxillofacial surgery | 21 |
| Hematology | 20 |
| Pharmacy | 20 |
| Dentist | 18 |
| Neuropsychiatry | 17 |
| Oral surgery (dentists only) | 16 |
| Hematopoietic Cell Transplantation and Cellular Therapy | 14 |
| Portable X-Ray Supplier (Billing Independently) | 14 |
| Preventive medicine | 13 |
| Micrographic Dermatologic Surgery | 9 |
| Epileptologists | 9 |
| Single or Multispecialty Clinic or Group Practice | 9 |
| Addiction medicine | 7 |
| All other suppliers, e.g., Drug Stores | 5 |
| Osteopathic manipulative therapy | 5 |
| Nuclear medicine | 4 |
| Medical Genetics and Genomics | 4 |
| Adult Congenital Heart Disease | 3 |
| Unknown physician specialty | 2 |
| Home Infusion Therapy Services | 2 |
| Psychologist (billing independently) | 2 |
| Peripheral vascular disease | 1 |
| Slide Preparation Facilities | 1 |
| Undersea and Hyperbaric Medicine | 1 |
| Prosthodontics | 1 |
| Medicare Diabetes Preventive Program | 1 |
| Unknown Provider | 1 |
| None | 1 |