| Nurse practitioner | 9,920 |
| Physical therapist (private practice) | 4,341 |
| Physician assistant | 4,116 |
| Internal medicine | 3,855 |
| Family practice | 3,534 |
| Licensed clinical social worker | 2,708 |
| Emergency medicine | 2,082 |
| Chiropractic | 1,989 |
| Certified Registered Nurse Anesthetist (CRNA) | 1,944 |
| Anesthesiology | 1,760 |
| Mental Health Counselors | 1,490 |
| Optometrist | 1,476 |
| Clinical psychologist | 1,389 |
| Obstetrics/gynecology | 1,379 |
| Diagnostic Radiology | 1,295 |
| Hospitalist | 1,206 |
| Psychiatry | 977 |
| Podiatry | 839 |
| General surgery | 818 |
| Mass Immunization Roster Billers | 816 |
| Occupational therapist (private practice) | 791 |
| Orthopedic surgery | 774 |
| Neurology | 719 |
| Cardiology | 713 |
| Ophthalmology | 680 |
| Gastroenterology | 635 |
| Ambulance Service Supplier, e.g., private ambulance companies, funeral homes | 553 |
| Pathology | 550 |
| Centralized Flu | 515 |
| Hematology/oncology | 473 |
| Dermatology | 471 |
| Pulmonary disease | 458 |
| Nephrology | 421 |
| Audiologist (billing independently) | 371 |
| Physical medicine and rehabilitation | 366 |
| Otolaryngology | 361 |
| Urology | 360 |
| Speech / language pathology | 327 |
| Pediatric medicine | 317 |
| Infectious disease | 294 |
| Endocrinology | 278 |
| Interventional Cardiology | 260 |
| Registered Dietician/Nutrition Professional | 236 |
| Critical care (intensivists) | 230 |
| Rheumatology | 224 |
| Radiation oncology | 209 |
| Neurosurgery | 195 |
| Plastic and reconstructive surgery | 173 |
| Clinical Laboratory (Billing Independently) | 167 |
| Certified nurse midwife | 160 |
| Allergy/immunology | 156 |
| Ambulatory Surgical Center | 140 |
| Vascular surgery | 136 |
| Certified clinical nurse specialist | 131 |
| Cardiac Electrophysiology | 129 |
| Thoracic surgery | 102 |
| Sports Medicine | 99 |
| Medical oncology | 98 |
| Independent Diagnostic Testing Facility (IDTF) | 97 |
| Interventional radiology | 95 |
| Pain Management | 91 |
| General practice | 86 |
| Hand surgery | 85 |
| Marriage and Family Therapist | 74 |
| Geriatric medicine | 74 |
| Hospice and Palliative Care | 71 |
| Colorectal surgery (formerly proctology) | 65 |
| Pharmacy | 61 |
| Opioid Treatment Program | 55 |
| Surgical oncology | 53 |
| Advanced Heart Failure and Transplant Cardiology | 51 |
| Sleep Medicine | 50 |
| Cardiac surgery | 50 |
| Interventional Pain Management (IPM) | 46 |
| Gynecologist/oncologist | 39 |
| Maxillofacial surgery | 35 |
| Oral surgery (dentists only) | 32 |
| Hematology | 24 |
| Dentist | 22 |
| Single or Multispecialty Clinic or Group Practice | 19 |
| Neuropsychiatry | 18 |
| Preventive medicine | 16 |
| Portable X-Ray Supplier (Billing Independently) | 15 |
| Hematopoietic Cell Transplantation and Cellular Therapy | 14 |
| Micrographic Dermatologic Surgery | 12 |
| Epileptologists | 12 |
| Addiction medicine | 11 |
| Osteopathic manipulative therapy | 9 |
| Anesthesiologist Assistant | 7 |
| Nuclear medicine | 6 |
| All other suppliers, e.g., Drug Stores | 6 |
| Medical Genetics and Genomics | 6 |
| Home Infusion Therapy Services | 5 |
| Undersea and Hyperbaric Medicine | 4 |
| Adult Congenital Heart Disease | 4 |
| Unknown physician specialty | 3 |
| Unknown Provider | 2 |
| Psychologist (billing independently) | 2 |
| Peripheral vascular disease | 1 |
| Slide Preparation Facilities | 1 |
| Prosthodontics | 1 |
| Medicare Diabetes Preventive Program | 1 |
| General Psychiatry | 1 |
| Intensive Cardiac Rehabilitation | 1 |
| None | 1 |