This bill, known as the "21st Century Worker Act," aims to establish clear and consistent federal standards for classifying workers as either employees or independent contractors . It introduces a bifurcated classification system, categorizing service provider payees into mandatory independent contractors, mandatory employees, or elective classification service provider payees. The legislation also mandates that these new definitions be applied to various existing federal laws, thereby standardizing worker classification across different legal contexts. The bill defines specific criteria for mandatory independent contractor classification , including licensed professionals holding themselves out to the public, business entities, those in limited economic relationships, direct sales service providers, bona fide sole proprietors, and formal bona fide contractors. Conversely, a service provider payee is classified as a mandatory employee if they are in a substantial economic relationship with the service recipient payor or if there is an explicit employment by agreement. The initial classification determination is generally the responsibility of the service recipient payor, with some exceptions for the service provider payee. For service provider payees who do not meet the criteria for either mandatory classification, the bill creates an elective classification category. These individuals must make a written election to be classified as either an employee or an independent contractor, which requires both the payee's signature and the payor's countersignature. Penalties are outlined for failing to make an election, maintain records, or for willful or reckless misclassification, with a default classification as an independent contractor if a countersignature is not secured. The legislation also includes provisions for reclassification and periodic review of worker status. A new classification determination is required if there is a major change in the economic relationship, defined as a 25 percent or more increase or decrease in hours worked or compensation. Other significant changes, such as the loss of a license or a change in exclusivity requirements, also trigger a review. Additionally, annual periodic reviews are mandated for continuing economic relationships, with an exemption for relationships involving less than 100 hours worked or $10,000 in compensation per quarter. Finally, Title II of the bill addresses the application of these new definitions to other federal laws . It amends the definitions of "employee" and "employer" in the Fair Labor Standards Act of 1938, the National Labor Relations Act, and the Internal Revenue Code to align with the new framework. The bill also directs the Comptroller General to conduct a study identifying other federal laws that use these terms differently and to analyze the impact of harmonizing these definitions across all covered federal statutes.