Do tariffs raise the effective tax rate on new investment?
Core argument: Tariffs in force before the February 20, 2026 Supreme Court ruling in Learning Resources v. Trump raised the economy-wide marginal effective tax rate on new US investment by 4.2 points, from 12.8 percent to 17.0 percent, and the cost of capital by 2.7 percent, the AEI authors estimate.
The standard Hall-Jorgenson user cost of capital framework defines the minimum gross required return on an additional unit of capital. The service price of capital (SS) is the minimum pretax gross return required on a new investment; the minimum pretax net return (ρrho) equals SS minus economic depreciation. Consider imported equipment requiring a 25% gross return: 20% to cover depreciation and 5% shareholders’ demanded return. A 10% tariff raises the cost of capital to 27.5%. [Thus the minimum pretax net return—the hurdle rate—rises from 5% to 7.5%]. For equipment, tariffs raise the cost of capital 9%, from 17.7% to 19.3%: 86% of the burden is direct, 14% indirect. 100% bonus depreciation reduced the equipment METR from 19.1% to 4.1%; tariffs raised it to 30.3%, more than offsetting the tax cut.


