In 2005, the Congressional Budget Office (CBO) released a paper called "Analyzing the Economic and Budgetary Effects of a 10 Percent Cut in Income Tax Rates". This paper considered the impact of a stylized reduction of 10% in the then existing marginal rate of federal income tax in the US (for example, if those facing a 25% marginal federal income tax rate had it lowered to 22.5%). Unlike earlier research, the CBO paper estimates the budgetary impact of possible macroeconomic effects of tax policies, that is, it attempts to account for how reductions in individual income tax rates might affect the overall future growth of the economy, and therefore influence future government tax revenues; and ultimately, impact deficits or surpluses.
The paper's author forecasts the effects using various assumptions (e.g., people's foresight, the mobility of capital, and the ways in which the federal government might make up for a lower percentage revenue). In the paper's most generous estimated growth scenario, only 28% of the projected lower tax revenue would be recouped over a 10-year period after a 10% across-the-board reduction in all individual income tax rates. The paper points out that these projected shortfalls in revenue would have to be made up by federal borrowing: the paper estimates that the federal government would pay an extra $200 billion in interest over the decade covered by the paper's analysis.[4]
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