This chapter examines the treatment of trade and domestic taxes in a computable general equilibrium (CGE) model. Trade taxes are imposed on imports and exports of goods and services. Domestic taxes are taxes paid by production activities on output and factor use and by purchasers on sales of intermediate and retail goods, and income taxes. We trace the tax data in a Social Accounting Matrix (SAM) to describe the agent and the economic activity on which the tax is levied and the amount of revenue generated by each tax; we also show how to use the SAM’s data to calculate tax rates. Partial equilibrium diagrams then illustrate the theoretical effects of taxes on economic activity and welfare. The results of tax policy experiments using a CGE model support the theoretical predictions and offer insight into the economywide effects of each tax. Three applied examples of tax policy analysis explore the second-best welfare effects of a tax, the marginal welfare impacts of a country’s entire tax structure, and the elimination of import tariffs in a preferential trade agreement.