关税作为财政政策（英）

Kimberly A. Clausing and Maurice ObstfeldSeptember 2025 ABSTRACT The year 2025 brought a remarkable shift in the role of tariffs in the US economy,as the Trump administration simultaneously escalated the use of broad tariffsand ensured that Congress enacted large income tax cuts. This fiscal switch hasimportant implications for the US tax system. While maintaining tariff rates atsummer 2025 levels would generate large government revenues, such broadtariffs have significant downsides: Efficiency losses would approach one-thirdof revenues raised, the tax system would be less progressive, and there wouldbe serious tax administration concerns. The fiscal shift also has significantmacroeconomic implications, although probably not the intended ones. Broadtariffs generate a large negative supply shock, simultaneously raising prices andreducing macroeconomic activity. Kimberly Clausingis theEric M. Zolt Professor ofTax Law and Policy atUniversity of California, LosAngeles, and a nonresidentsenior fellow at thePeterson Institute forInternational Economics. Maurice Obstfeldis theC. Fred Bergsten SeniorFellow at the PetersonInstitute for InternationalEconomics and the Classof 1958 Professor ofEconomics Emeritus atUniversity of California,Berkeley. JEL Codes:F13, F32, F38, F42, F52, H21, H23, H26, H68, L52Keywords:Tariffs, revenue, deadweight loss, optimal tariff, pass-through, rent-seeking, retaliation, redistribution, industrial policy Authors’ Note:This paper is forthcoming (March 2026) in theNational Tax Journal. Wethank Greg Auclair, Olivier Blanchard, Nell Henderson, Mary Lovely, Marcus Noland,Andrés Rodríguez-Clare, Ernest Tedeschi, Nicolas Véron, and participants in the UCLASchool of Law colloquium and the PIIE research seminar for helpful discussions. Wethank Nolan Jones, Serra Pelin, and Shane Ball for helpful research assistance. I.Introduction With the election of Donald Trump to a second (nonconsecutive) term in November 2024, itbecame clear that tariffs would play a much larger role in US economic policy. Trump’s firstterm saw a large expansion of the use of tariffs, with tariff revenues nearly doubling relative toimports, but his 2024 campaign promised a far larger role for tariffs. In the early days of 2025,the effective tariff rate soared from under 3 percent at the end of the Biden administration toover 20 percent; as of September 4, 2025 it stood at about 17.5 percent (Budget Lab 2025a),the highest level since 1935. The future of tariffs remains unclear; Congress has yet to legislateregarding tariffs, and legal challenges against many of the tariffs are underway. Nonetheless,we expect these issues to be relevant for policy discussions for some time.1 Source: Data on customs duties and imports are from the US Bureau of Economic Analysis. The2025 tariff rate is fromBudget Lab (2025a). Actual revenues may be lower than those impliedby this rate due to myriad exemptions, discussed below. While tariffs have been an intriguing tool for policymakers of both parties, the recent increasein the use of US tariffs has introduced an important public debate about their place in nationaleconomic policy. We focus in this paper on defensible arguments2about possible roles fortariffs, considering first conventional uses of tariffs long discussed in the modern tariffliterature. We then examine the present approach of using tariffs as a fiscal policy instrument. The broad use of tariffs by the current Trump administration is novel. It marks a departure fromthe modern practice in rich countries, where tariffs have a very minimal scale and role; for high-income OECD countries, tariffs account for a mere 1.25 percent of the value of goods imports,and less than 2 percent of government revenues.3Even more noteworthy, the Trumpadministration’s use of tariffs is part of a larger fiscal switch that moves tax burdens away fromthe income tax and toward import taxes (tariffs). The tariffs in place as of this writing wouldgenerate large revenues. Therefore, together with Trump’s 2025 changes in tax law under the“One Big Beautiful Bill Act” (OBBBA), which not only extend the expiring tax cuts from the 2017“Tax Cuts and Jobs Act” legislation but also enact a broad array of new income tax cuts, 2025marks an important shift in how the US government is funded. In this paper, we evaluate this US fiscal shift according to standard tax policy criteria, focusingon revenue, distribution, efficiency, and tax administration. As of the summer of 2025, theTrump tariffs are on track to raise substantial revenues. Still, even at revenue-maximizing rates,tariffs would generate less than one-fifth the revenue of the federal income tax, and at suchhigh tariff rates, efficiency losses would be nearly as great as the revenue raised. Even at tariffrates of 20 percent, efficiency losses are about one-third of revenue raised. The present fiscal switch also affects the distribution of tax burdens in the United States. The2025 tax legislation (