In this paper, we present a review of tax research. We survey four main areas of the literature: (1) the informational role of income tax expense reported for financial accounting, (2) corporate tax avoidance, (3) corporate decision-making including investment, capital structure, and organizational form, and (4) taxes and asset pricing. We summarize the research areas and questions examined to date and what we have learned or not learned from the work completed thus far. In addition, we provide our opinion as to the interesting and important issues for future research.