| Nurse practitioner | 3,032 |
| Physician assistant | 2,303 |
| Family practice | 1,626 |
| Internal medicine | 1,258 |
| Physical therapist (private practice) | 1,195 |
| Certified Registered Nurse Anesthetist (CRNA) | 1,189 |
| Licensed clinical social worker | 1,169 |
| Chiropractic | 978 |
| Mental Health Counselors | 852 |
| Emergency medicine | 677 |
| Clinical psychologist | 642 |
| Optometrist | 524 |
| Marriage and Family Therapist | 504 |
| Diagnostic Radiology | 492 |
| Anesthesiology | 463 |
| Obstetrics/gynecology | 446 |
| Psychiatry | 356 |
| Orthopedic surgery | 330 |
| Mass Immunization Roster Billers | 305 |
| Occupational therapist (private practice) | 303 |
| General surgery | 298 |
| Cardiology | 288 |
| Neurology | 258 |
| Ophthalmology | 234 |
| Pathology | 211 |
| Gastroenterology | 206 |
| Dermatology | 181 |
| Hospitalist | 171 |
| Pediatric medicine | 162 |
| Audiologist (billing independently) | 156 |
| Physical medicine and rehabilitation | 143 |
| Pulmonary disease | 142 |
| Podiatry | 140 |
| Registered Dietician/Nutrition Professional | 138 |
| Hematology/oncology | 130 |
| Nephrology | 129 |
| Speech / language pathology | 126 |
| Otolaryngology | 120 |
| Certified nurse midwife | 113 |
| Urology | 111 |
| Ambulance Service Supplier, e.g., private ambulance companies, funeral homes | 108 |
| Centralized Flu | 97 |
| Infectious disease | 86 |
| Medical oncology | 84 |
| Endocrinology | 72 |
| Certified clinical nurse specialist | 70 |
| Radiation oncology | 66 |
| Rheumatology | 65 |
| Neurosurgery | 63 |
| Critical care (intensivists) | 59 |
| Sports Medicine | 54 |
| Ambulatory Surgical Center | 52 |
| Plastic and reconstructive surgery | 41 |
| Allergy/immunology | 40 |
| Vascular surgery | 40 |
| Hematology | 36 |
| Interventional Cardiology | 35 |
| Hospice and Palliative Care | 35 |
| Cardiac Electrophysiology | 34 |
| Oral surgery (dentists only) | 34 |
| Colorectal surgery (formerly proctology) | 32 |
| Interventional radiology | 29 |
| Maxillofacial surgery | 28 |
| Geriatric medicine | 26 |
| Pain Management | 24 |
| Thoracic surgery | 23 |
| Hand surgery | 22 |
| Pharmacy | 20 |
| Clinical Laboratory (Billing Independently) | 19 |
| Gynecologist/oncologist | 15 |
| Advanced Heart Failure and Transplant Cardiology | 15 |
| Sleep Medicine | 15 |
| Cardiac surgery | 15 |
| Micrographic Dermatologic Surgery | 14 |
| Dentist | 14 |
| Interventional Pain Management (IPM) | 13 |
| Addiction medicine | 11 |
| Opioid Treatment Program | 11 |
| Preventive medicine | 11 |
| Epileptologists | 11 |
| General practice | 10 |
| Independent Diagnostic Testing Facility (IDTF) | 6 |
| Medical Genetics and Genomics | 6 |
| Neuropsychiatry | 4 |
| Portable X-Ray Supplier (Billing Independently) | 3 |
| Surgical oncology | 3 |
| Unknown Provider | 3 |
| Undersea and Hyperbaric Medicine | 3 |
| Prosthodontics | 3 |
| Anesthesiologist Assistant | 2 |
| Nuclear medicine | 2 |
| Home Infusion Therapy Services | 2 |
| Osteopathic manipulative therapy | 2 |
| Orthodontics and Dentofacial Orthopedics | 1 |
| Unknown physician specialty | 1 |
| Medicare Diabetes Preventive Program | 1 |
| Single or Multispecialty Clinic or Group Practice | 1 |
| General Psychiatry | 1 |
| Peripheral vascular disease | 1 |
| Psychologist (billing independently) | 1 |