国会预算办公室2025财年预算预测的准确性

JANUARY | 2026 After each fiscal year ends, the Congressional BudgetOffice reviews its projections of federal revenues andoutlays and the government’s budget deficit and com-pares them with actual budgetary outcomes for that year.Comparing CBO’s projections with actual outcomes iscomplicated by changes in law and administrative andjudicial actions that occur after the projections are made.By statute, CBO’s projections do not include forecasts offuture changes in law. The agency also does not attemptto predict judicial rulings and nonroutine changes inadministrative policy. Following a long-standing agree-ment between CBO and the House and Senate BudgetCommittees, if the Administration has not taken a clear,official, and public action that details a proposed change,CBO does not include the budgetary effects of thatchange in its baseline projections. administrative actions.2Indeed, customs duties aloneaccount for about half of the difference between actualrevenues in 2025 and CBO’s January 17, 2025 projectionof revenues. One simplified way to isolate the effects of tariff changesand focus on factors that the agency attempted to esti-mate is to exclude customs duties from total revenues.3Excluding customs duties, the actual federal budget deficitwas $95 billion smaller than CBO projected it wouldbe in June 2024 (seeTable 1). That amount is equal to0.3 percent of gross domestic product (GDP), which isabout three-tenths as large as the average error over theprevious 40 years (in absolute terms). The actual deficitexcluding customs duties was $13 billion larger thanCBO projected it would be in January 2025. The largestcontributors to the difference between the actual deficitexcluding customs duties and CBO’s January projectionswere an underestimate of revenues from individual incometaxes and underestimates of outlays attributable to higher-than-expected outlays for Medicaid and Medicare. The many changes to tariffs in 2025 illustrate the conse-quences of holding administrative policies unchanged inCBO’s baseline. The projections of revenues from cus-toms duties reflect the estimated effects of tariffs in placewhen the projections were finalized and incorporate theassumption that those tariffs continue without furtherchanges.1Specifically, the projection of customs duties inCBO’s January 2025 projections is based on the tariffsin place on January 17, 2025. Actual tariff revenues in2025 were much higher, reflecting the higher tariff ratesput in place by administrative action after January 20,2025. Customs duties accounted for 4 percent of reve-nue in 2025, whereas they accounted for only 2 percentin 2024. The difference between actual revenues fromcustoms duties ($195 billion) and CBO’s January pro-jections ($76 billion) almost entirely stems from those Historically, CBO’s measures of accuracy have catego-rized the effects from nonroutine changes in administra-tive policy (such as those regarding tariffs) as projectionerrors because they can be difficult to separate from othereffects. The body of this report maintains that conven-tion and includes differences in revenues resulting from Accuracy of CBO’s June 2024 and January 2025 Baseline Projections for 2025,With and Without Customs Duties The budget projections presented here are based on projections published in Congressional Budget Office,The Budget and Economic Outlook: 2025 to2035(January 2025),www.cbo.gov/publication/60870, andAn Update to the Budget and Economic Outlook: 2024 to 2034(June 2024),www.cbo.gov/publication/60039. For this analysis, CBO updated those projections to account for the budgetary effects of subsequent legislation as estimated around the timeof its enactment. For discretionary spending, the amounts reflect estimated outlays stemming from full-year appropriations provided for 2025. The projectionsare generally consistent with the technical assessments (of, for example, how quickly appropriations will be spent) and economic projections underlying theJune 2024 baseline projections. The projected discretionary spending amounts include outlays estimated for 2025 from supplemental appropriations made in2024 and 2025. Many of those estimates incorporated updated technical assessments. ** = between -0.05 percent and zero. a.For outlay and revenue projections, the difference is the projected amount minus the actual amount. For deficit projections, the difference is the actualamount minus the projected amount. For all three types of projections, a negative amount indicates an underestimate. b.For outlay and revenue projections, the projection error is the difference divided by the actual amount. For deficit projections, the percentage error is theprojection error divided by gross domestic product (GDP). c.The average absolute error is an average of projection errors without regard to whether they are positive or negative. The budget year is the second yearof the period covered by CBO’s baseline projections; it usually begins several mo