Medicare Part B reimbursement and service volume differences between ambulatory nurse practitioners and physicians

Nurse practitioners (NPs) increasingly deliver ambulatory care, yet state scope of practice (SoP) laws influence how their services are billed and utilized within Medicare. To compare Medicare reimbursement and service volume for ambulatory NPs and physicians by state SoP regulations. We analyzed 100% of 2021 Medicare Part B claims, attributing claims to individual providers. Adjusted regression models estimated cost and service differentials by provider type and state SoP status. NPs in full SoP states had higher Medicare cost and more services per beneficiary than those in restricted states. Among physicians, cost and service volume did not differ by SoP. Expanded practice authority for NPs increases access without reducing physician service delivery or reimbursement. State SoP regulations shape ambulatory care delivery. Greater NP autonomy may improve system sustainability by increasing access to NP reimbursed services without shifting current physician reimbursement from Medicare.