What act established NPI numbers?

Explanation:

The act that established NPI (National Provider Identifier) numbers is the Patient Protection and Affordable Care Act (PPACA), also known simply as the Affordable Care Act (ACA). The PPACA was enacted on March 23, 2010, as a comprehensive healthcare reform to increase health insurance quality and affordability, lower the uninsured rate, and reduce the costs of healthcare for individuals and the government.

The use of NPI numbers was part of the administrative simplification provisions of Health Insurance Portability and Accountability Act of 1996 (HIPAA), which mandated that the U.S. Department of Health and Human Services (HHS) create a standardized identifier for health care providers. The NPI is a unique 10-digit identification number issued to health care providers in the United States by the Centers for Medicare and Medicaid Services (CMS).

The National Federation of Independent Business v. Sebelius case, which was a challenge to the PPACA, did affirm the power of Congress under its taxing authority to implement certain aspects of the PPACA, such as the individual mandate to acquire health insurance.