I study how people understand, reason, and learn about tax policy. The goal is to uncover the mental models that people use to think about income and estate taxes. To that end, I run largescale online surveys and experiments on representative U.S. samples to elicit not only respondents’ factual knowledge about tax policy and the income or wealth distributions, but also their understanding of the mechanisms of tax policy and their reasoning about it. The detailed survey questions are designed to address the three main factors emphasized in our core tax model that can shape support for or opposition to taxes: efficiency effects, distributional implications, and fairness considerations. But they also elicit broader concerns that could influence policy views such as misperceptions, views of government, perceived spillovers from taxes, and views on how tax revenues are or should be spent. To extract people’s first-order considerations that come to mind when they are prompted to think about tax policy, its shortcomings, and goals without priming them, open-ended questions are used and then evaluated with text analysis methods. There are partisan divergences not just in the final policy views, but also in reasonings about the underlying mechanisms and most starkly on the fairness considerations. I decompose policy views into the various underlying factors and find that support for tax policy is most strongly correlated with views on the benefits of redistribution and fairness, as well as with views of the government. Efficiency concerns play a more minor role. These correlational patterns are confirmed by the experimental approach, which shows people instructional videos that explain the workings and consequences of one of the aspects of tax policy (the “Redistribution” and the “Efficiency” treatments) or that bring the two together and focus on the trade-off (the “Economist” treatment). The Redistribution treatment and Economist treatments significantly increase support for more progressive taxes.