| Nurse practitioner | 4,867 |
| Physician assistant | 2,733 |
| Internal medicine | 2,678 |
| Licensed clinical social worker | 2,266 |
| Physical therapist (private practice) | 1,707 |
| Family practice | 1,033 |
| Mental Health Counselors | 1,016 |
| Anesthesiology | 992 |
| Clinical psychologist | 950 |
| Psychiatry | 914 |
| Emergency medicine | 903 |
| Diagnostic Radiology | 812 |
| Certified Registered Nurse Anesthetist (CRNA) | 725 |
| Optometrist | 634 |
| Obstetrics/gynecology | 602 |
| Neurology | 510 |
| Chiropractic | 498 |
| Cardiology | 495 |
| Hospitalist | 445 |
| Orthopedic surgery | 397 |
| Mass Immunization Roster Billers | 391 |
| Ophthalmology | 355 |
| Gastroenterology | 351 |
| General surgery | 350 |
| Pathology | 345 |
| Dermatology | 345 |
| Pulmonary disease | 282 |
| Pediatric medicine | 282 |
| Hematology/oncology | 249 |
| Endocrinology | 229 |
| Podiatry | 207 |
| Infectious disease | 204 |
| Otolaryngology | 191 |
| Ambulance Service Supplier, e.g., private ambulance companies, funeral homes | 187 |
| Occupational therapist (private practice) | 182 |
| Medical oncology | 177 |
| Nephrology | 175 |
| Centralized Flu | 172 |
| Urology | 165 |
| Audiologist (billing independently) | 159 |
| Certified nurse midwife | 149 |
| Physical medicine and rehabilitation | 148 |
| Rheumatology | 144 |
| Certified clinical nurse specialist | 127 |
| Registered Dietician/Nutrition Professional | 123 |
| Radiation oncology | 101 |
| Neurosurgery | 101 |
| Critical care (intensivists) | 90 |
| Allergy/immunology | 87 |
| Vascular surgery | 82 |
| Plastic and reconstructive surgery | 82 |
| Speech / language pathology | 68 |
| Hospice and Palliative Care | 68 |
| Oral surgery (dentists only) | 60 |
| Geriatric medicine | 55 |
| Thoracic surgery | 53 |
| Independent Diagnostic Testing Facility (IDTF) | 52 |
| Ambulatory Surgical Center | 45 |
| Pharmacy | 45 |
| Cardiac Electrophysiology | 43 |
| Interventional Cardiology | 41 |
| Interventional radiology | 38 |
| Marriage and Family Therapist | 37 |
| Hand surgery | 36 |
| Sports Medicine | 35 |
| Pain Management | 34 |
| Hematology | 33 |
| Surgical oncology | 32 |
| Colorectal surgery (formerly proctology) | 29 |
| Clinical Laboratory (Billing Independently) | 26 |
| Cardiac surgery | 25 |
| General practice | 24 |
| Advanced Heart Failure and Transplant Cardiology | 24 |
| Maxillofacial surgery | 19 |
| Sleep Medicine | 18 |
| Dentist | 16 |
| Addiction medicine | 16 |
| Epileptologists | 15 |
| Gynecologist/oncologist | 14 |
| General Psychiatry | 12 |
| Public Health or Welfare Agencies (Federal, State, and local) | 11 |
| Opioid Treatment Program | 9 |
| Single or Multispecialty Clinic or Group Practice | 7 |
| Micrographic Dermatologic Surgery | 7 |
| Preventive medicine | 7 |
| Osteopathic manipulative therapy | 6 |
| Medical Genetics and Genomics | 5 |
| Nuclear medicine | 5 |
| Interventional Pain Management (IPM) | 5 |
| Home Infusion Therapy Services | 4 |
| Adult Congenital Heart Disease | 4 |
| Neuropsychiatry | 3 |
| Portable X-Ray Supplier (Billing Independently) | 1 |
| Oral and Maxillofacial Pathology | 1 |
| Anesthesiologist Assistant | 1 |
| Medicare Diabetes Preventive Program | 1 |
| Orofacial Pain | 1 |
| Peripheral vascular disease | 1 |