Final answer:
When billing Medicare, a Nurse Practitioner (NP) obtains the authority to bill through a process that includes obtaining a National Provider Identifier (NPI) and meeting state licensure requirements.
Step-by-step explanation:
A Nurse Practitioner gains the authority to bill Medicare by obtaining an NPI, complying with state licensure, registering with CMS, and acquiring a PTAN.
Following these steps, the NP may bill Medicare directly for services that are covered and within the scope of their practice. Registration with the Centers for Medicare & Medicaid Services (CMS) is also required to obtain a Medicare Provider Transaction Access Number (PTAN), which is a Medicare-specific identifier issued to providers.