This document,1 prepared by the staff of the Joint Committee on Taxation ("Joint Committee staff"), provides an analysis of the macroeconomic effects of a proposal to modify both the individual and corporate income tax by broadening their tax bases and changing statutory tax rates. This analysis is based on the proposal as it corresponds to the estimates presented in Estimated Revenue Effects of the "Tax Reform Act of 2014" (JCX-20-14), February 26, 2014 (and described in Discussion Draft CAMP_041). The following analysis uses both an overlapping generations lifecycle model and the Joint Committee staff's Macroeconomic Equilibrium Growth model to simulate the macroeconomic effects of the proposal. In general, the lower effective marginal tax rates resulting from the combination of lower statutory tax rates and changes to the definition of taxable income provide an incentive for increased labor effort, and under some modeling assumptions for some years, increased business investment. Relative to present law, the policy provides an incentive for increased consumer purchases of goods and services by increasing after-tax income of households. This effect can be important when the economy is operating below full capacity. The extent of both supply and demand effects depends on the sensitivity of individual labor choices to changing effective marginal rates, the responsiveness of individual savings choices to changes in the after-tax return on earnings from investment, and the responsiveness of businesses to changing incentives for overall investment and the location of investment and taxable profits in the United States. In addition, the projected impacts of the proposal on the economy depend on assumptions about the monetary policy response by the Federal Reserve Board. In general, under most modeling assumptions, the proposal is projected to increase overall economic activity as measured by changes in gross domestic product ("GDP") relative to the present law baseline over the 10-year budget period.