| Nurse practitioner | 5,342 |
| Internal medicine | 4,730 |
| Physical therapist (private practice) | 4,066 |
| Physician assistant | 3,863 |
| Licensed clinical social worker | 2,368 |
| Anesthesiology | 1,939 |
| Emergency medicine | 1,818 |
| Psychiatry | 1,698 |
| Family practice | 1,448 |
| Obstetrics/gynecology | 1,319 |
| Diagnostic Radiology | 1,280 |
| Clinical psychologist | 1,113 |
| Cardiology | 1,085 |
| Neurology | 888 |
| Podiatry | 881 |
| Occupational therapist (private practice) | 827 |
| Gastroenterology | 811 |
| Ophthalmology | 808 |
| Optometrist | 802 |
| Hospitalist | 777 |
| Certified Registered Nurse Anesthetist (CRNA) | 777 |
| General surgery | 715 |
| Mass Immunization Roster Billers | 621 |
| Orthopedic surgery | 609 |
| Dermatology | 606 |
| Pathology | 541 |
| Physical medicine and rehabilitation | 531 |
| Mental Health Counselors | 485 |
| Pulmonary disease | 435 |
| Chiropractic | 431 |
| Nephrology | 419 |
| Otolaryngology | 412 |
| Urology | 411 |
| Endocrinology | 407 |
| Infectious disease | 391 |
| Medical oncology | 369 |
| Pediatric medicine | 345 |
| Hematology/oncology | 314 |
| Speech / language pathology | 294 |
| Audiologist (billing independently) | 272 |
| Critical care (intensivists) | 249 |
| Rheumatology | 230 |
| Centralized Flu | 208 |
| Radiation oncology | 183 |
| Neurosurgery | 177 |
| Registered Dietician/Nutrition Professional | 171 |
| Pharmacy | 170 |
| Plastic and reconstructive surgery | 168 |
| Vascular surgery | 155 |
| Allergy/immunology | 143 |
| Certified nurse midwife | 136 |
| Geriatric medicine | 125 |
| General practice | 125 |
| Pain Management | 113 |
| Interventional radiology | 113 |
| Interventional Cardiology | 111 |
| Hospice and Palliative Care | 99 |
| Ambulance Service Supplier, e.g., private ambulance companies, funeral homes | 87 |
| Cardiac Electrophysiology | 85 |
| Thoracic surgery | 82 |
| Ambulatory Surgical Center | 70 |
| Hematology | 68 |
| Colorectal surgery (formerly proctology) | 66 |
| Sports Medicine | 64 |
| Gynecologist/oncologist | 57 |
| Clinical Laboratory (Billing Independently) | 54 |
| Advanced Heart Failure and Transplant Cardiology | 54 |
| Surgical oncology | 50 |
| Cardiac surgery | 48 |
| Oral surgery (dentists only) | 47 |
| Hand surgery | 43 |
| Independent Diagnostic Testing Facility (IDTF) | 41 |
| Nuclear medicine | 40 |
| Marriage and Family Therapist | 32 |
| Opioid Treatment Program | 31 |
| Interventional Pain Management (IPM) | 30 |
| Osteopathic manipulative therapy | 24 |
| Sleep Medicine | 23 |
| Maxillofacial surgery | 20 |
| Neuropsychiatry | 17 |
| Dentist | 16 |
| Preventive medicine | 12 |
| Medical Genetics and Genomics | 10 |
| Hematopoietic Cell Transplantation and Cellular Therapy | 10 |
| Micrographic Dermatologic Surgery | 9 |
| Single or Multispecialty Clinic or Group Practice | 8 |
| Addiction medicine | 8 |
| Unknown physician specialty | 6 |
| Adult Congenital Heart Disease | 6 |
| Portable X-Ray Supplier (Billing Independently) | 5 |
| Certified clinical nurse specialist | 5 |
| Medical Toxicology | 5 |
| Oral and Maxillofacial Pathology | 3 |
| General Psychiatry | 3 |
| Home Infusion Therapy Services | 3 |
| All other suppliers, e.g., Drug Stores | 3 |
| Epileptologists | 2 |
| Undersea and Hyperbaric Medicine | 1 |
| Psychologist (billing independently) | 1 |
| Oral Medicine | 1 |
| Medicare Diabetes Preventive Program | 1 |