The Medicare Fraud Detection and Deterrence Act of 2025 seeks to enhance efforts against health care waste, fraud, and abuse within federal programs. A key provision mandates the deactivation of National Provider Identifiers (NPIs) for individuals and, under certain conditions, organizations that have been excluded from participation in any federal health care program. This deactivation will last for the entire duration of the exclusion, preventing such entities from billing for services. The Secretary is also required to conduct annual reviews to ensure compliance by comparing exclusion lists with active NPIs. Furthermore, the bill introduces new requirements for Medicare Advantage plans , stipulating that encounter data for designated items or services must include the NPI of the ordering or referring provider. These designated services encompass durable medical equipment, prosthetic devices, clinical diagnostic laboratory tests, diagnostic imaging, and home health services. The Secretary is directed to reject any encounter data that fails to meet this requirement or includes an inactive or invalid NPI, thereby improving oversight and accountability. Finally, the legislation addresses telehealth services by requiring the establishment of a new claims modifier . This modifier will identify telehealth services furnished by physicians or practitioners who have an employment or contractual relationship with a "telehealth company," defined as an entity primarily providing telehealth services. Payment for such services will be contingent upon the inclusion of this modifier, allowing for better tracking and analysis of telehealth provision models.