These documents provide a description of the Tax Policy Center's microsimulation model of the federal tax system and materials to help understand and interpret our estimates.

• Microsimulation Model FAQ
  Answers to common questions about TPC's tax simulation model, the estimates it generates, and the organization of tables in our database.
• Brief Description of the Tax Model
  The Urban-Brookings Tax Policy Center’s large-scale microsimulation model produces revenue and distribution estimates of the U.S. federal tax system.
• Description of TPC’s Business Tax Model
  The Urban-Brookings Tax Policy Center’s business tax model is used to estimate the effects of tax proposals on federal revenue, incentives to invest, choices related to the source of financing (i.e., debt vs. equity) and form of business organization (e.g., corporate vs. pass-through), and tax burdens across firms and industries.
• Description of TPC’s Tariff Models
  This page provides more information about the methodologies TPC uses to analyze tariffs, including the rules engine and how TPC estimates the revenue and distributional effects of tariff policy. It also documents the policy and technical changes underlying TPC's tariff rules engine.
• Brief Description of the State Tax Model
  The State Tax Model allows TPC to analyze how federal tax law changes effect households at various income levels in different states.
• TPC’s Methodology for “Off-Model” Revenue Estimates
  This paper describes how TPC produces most other off-model revenue estimates.
• Measuring the Distribution of Tax Changes
  TPC's distribution tables provide quantitative information on the way in which tax proposals affect different groups of individuals. At TPC, we proceed on the notion that a household's economic well-being, or welfare, is closely linked to its after-tax income. We also report several other measures in our distribution tables including the share of the tax cut received, and the size of the tax cut in both absolute dollars and as a percentage of initial tax liability.
• Income Measure Used in Distributional Analyses by the Tax Policy Center
  Tax Policy Center (TPC) uses a broad measure of pre-tax income, which we call “expanded cash income” or ECI, to analyze the distribution of federal taxes.
• TPC Baseline Definitions
  Current law refers to the law currently scheduled for a given year — that is, the law that will prevail if Congress does not act to change it. The definition of current law will typically change when Congress enacts a new tax law.