This book explores Evaluation and Management (E/M) coding and serves as a resource in the practice and application of level of service codes. For two decades the 1995 and 1997 guidelines have provided guidance and structure around the documentation requirements necessary to support professional, outpatient services. After twenty-three years, Medicare has announced the adoption of a new set of standards to be released on January 1, 2021. This book will serve as a guide for correct code assignment and as an educational resource for the 1995, 1997 and 2021 documentation guidelines.