Which U.S. act defines what counts as hours worked for the purpose of calculating overtime?

The Fair Labor Standards Act (FLSA) is the legislation that defines what counts as hours worked for the purpose of calculating overtime. Under the FLSA, hours worked include all the time employees are required to be on the employer's premises, on duty, or at an assigned workplace. This act establishes the federal minimum wage, overtime pay, recordkeeping, and youth employment requirements. Specifically, it outlines how to calculate overtime based on the standard rate of wages, which applies to all non-exempt employees.

While the Portal-to-Portal Act provides definitions and clarifications regarding activities that are compensable and under what circumstances additional hours are counted, the core definitions of hours worked, including the rules for calculating overtime, are primarily established by the Fair Labor Standards Act itself. The other options—including the Pregnancy Discrimination Act, which focuses on employment protections related to pregnancy, and the Energy Policy Act, which addresses energy regulations, as well as the Portal-to-Portal Act—do not pertain directly to the definition of work hours or overtime calculations.