国会预算办公室关于2017年税改延长及额外减收对赤字与债务影响的分析

Honorable Jeff MerkleyRanking MemberCommittee on the BudgetUnited States SenateWashington, DC 20510 Re: Projections of Deficits and Debt Under an Alternative Scenario for theBudget Dear Senator: This letter responds to your request for an analysis of projected deficits anddebt under an alternative scenario for the budget that reflects two changesto the Congressional Budget Office’s baseline. Specifically, you asked howCBO’s projections of deficits and debt would change if certain provisionsof the 2017 tax act (Public Law 115-97) were extended permanently.1(Bystatute, estimates of the effects of tax legislation are made by the staff of theJoint Committee on Taxation, or JCT.) You also asked how thoseprojections would change if revenues were reduced by an additional$150 billion in each year of the 10-year budget window and by a fixedpercentage of gross domestic product (GDP) thereafter. In CBO’s most recent extended baseline projections, which reflect theassumption that current laws generally remain unchanged, primary deficits(that is, deficits excluding net outlays for interest) average 2.0 percent ofGDP over the 2025–2055 period and equal 1.9 percent of GDP in 2055.2 Honorable Jeff MerkleyPage 2 Total deficits average 6.3 percent of GDP over that period and reach7.3 percent of GDP in 2055. Federal debt held by the public increases from100 percent of GDP to 156 percent of GDP—exceeding any previouslyrecorded level and on track to increase further.3 CBO estimates that if provisions of the 2017 tax act were extended, taxrevenues were lower by the additional amount you specified, and therewere no other changes to fiscal policy, debt held by the public would reach220 percent of GDP in 2055, 63 percentage points higher than in the long-term baseline projections. Interest rates would also be higher, and real grossnational product (GNP) per person—a measure of the resources available toU.S. households—would be lower in that year.4 Those estimates incorporate the economic effects that would result from theextension of provisions of the 2017 tax act and the additional reductions inrevenues that you specified. Those effects include increases in the supply oflabor and investment brought about by lower marginal tax rates on incomefrom labor and capital, increases in output in the short term caused bygreater overall demand for goods and services, and decreases in output inthe longer term caused by larger federal deficits and debt. A Scenario With Provisions of the 2017 Tax Act Extendedand Additional Reductions in Revenues You asked CBO to analyze the effects of an alternative budget scenario inwhich certain provisions of the 2017 tax act that changed the individualincome tax continue indefinitely: the lower statutory tax rates, the changesto allowable deductions, the larger child tax credit, the 20 percent deductionfor certain business income, and the income levels at which the alternativeminimum tax takes effect. CBO’s analysis also accounted for the effects ofpermanently extending the higher estate and gift tax exemptions, Honorable Jeff MerkleyPage 3 permanently extending provisions that allow businesses to immediatelydeduct the full cost of certain investments, and maintaining more generousrules for several business tax provisions. Many other provisions of the 2017tax act are permanent and are therefore reflected in CBO’s baselineprojections as well as in that alternative scenario. You also asked that revenues in the alternative scenario be reduced by anadditional $150 billion in each year of the 10-year budget window and by afixed percentage of GDP thereafter. Reductions in revenues can occurthrough many channels. To simplify the analysis, you asked CBO toassume that the reductions occur through a uniform refundable tax creditthat leaves incentives to work and invest unchanged.5 In that scenario, deficits and debt are larger than they are in CBO’sextended baseline (seeFigure 1): •Primary deficits over the first decade of the projection period (fiscalyears 2026 to 2035) are about $6 trillion larger. By 2055, theprimary deficit equals 3.8 percent of GDP, 1.9 percentage pointshigher than in CBO’s extended baseline. •The total deficit in 2055 equals 12.0 percent of GDP, 4.7 percentagepoints higher than in CBO’s extended baseline.•Debt held by the public in 2055 equals 220 percent of GDP,63 percentage points higher than in CBO’s extended baseline.•The average interest rate on federal debt in 2055 equals 4.0 percent,0.3 percentage points higher than in CBO’s extended baseline.•Real GNP per person is 3.3 percent lower in 2055 than in CBO’sextended baseline (or $4,375 lower, in 2025 dollars). Economic growth would be faster in the first several years after theextension of the tax provisions, primarily because of the increase in theoverall demand for goods and services. It would be slower in the longerterm: Although lower marginal tax rates would raise the supply of labor andinvestment by increasing the ince