This guide is part of a series of Virtual Training to Advance Revenue Administration (VITARA) reference guides that has been developed based on the contents of the VITARA online modules. This reference guide focuses on international good practices in organizational design. It explains how tax administrations can organize people, processes, and work effectively. It builds knowledge and understanding of critical features and dependencies in the organizational design of tax administrations, defining the concept of organizational design, and explaining why it is important. This guide also identifies the main organizational models (function-based, tax type-based, segment-based, and hybrid) used in the design of tax administrations and explains the advantages and disadvantages of the different models. It compares the roles of headquarters and field operations in a tax administration's organizational structure and also describes the importance of special units and functions within a tax administration's organizational structure. The guide helps tax administration leaders better understand how tax administration organizational models can be adapted to accommodate new responsibilities and roles.