At the start of 2020, Governor Jared Polis organized a Tax Study Group and charged it with analyzing the efficiency and equity of Colorado’s tax system. Over the course of the year, the Tax Study Group held five learning sessions. Throughout this process, the Urban Institute’s State and Local Finance Initiative, a project of the Urban-Brookings Tax Policy Center, shared its research expertise, microsimulation model data, and national and state policy perspectives with the group. This report summarizes that work.