This document is about the detailed methodology and data used by the U.S. Department of Labor to estimate the economic impacts and burden associated with the proposed modernization of the Form 5500 and its schedules, instructions, and attachments, commonly referred to as the Form 5500 21st Century Initiative. It provides a general overview of the estimation process, descriptions of data sources, calculation methods, and the resulting burden estimates by plan size, type, and entity (service provider vs. plan sponsor).