In Pollock v. Farmers' Loan & Trust Co. the Supreme Court of the United States declares unapportioned income tax to be unconstitutional.

Pollock v. Farmers' Loan & Trust Company, 157 U.S. 429 (1895), affirmed on rehearing, 158 U.S. 601 (1895), was a landmark case of the Supreme Court of the United States. In a 5-to-4 decision, the Supreme Court struck down the income tax imposed by the Wilson–Gorman Tariff Act for being an unapportioned direct tax. The decision was superseded in 1913 by the Sixteenth Amendment to the United States Constitution, which allows Congress to levy income taxes without apportioning them among the states.

Congress had previously introduced an income tax during the American Civil War, but this tax had been repealed in 1872. In 1894, Congress passed the Wilson-Gorman Tariff Act, which lowered tariff rates and made up for some of the lost revenue by introducing taxes on income, corporate profits, gifts, and inheritances. Chief Justice Melville Fuller's majority opinion in Pollock held that a federal tax on income derived from property was unconstitutional when it was not apportioned among the states according to representation in the House of Representatives. Fuller also held that federal taxation of interest earned on certain state bonds violated the doctrine of intergovernmental tax immunity. In one dissent, Associate Justice Henry Billings Brown wrote that the majority opinion "involves nothing less than the surrender of the taxing power to the moneyed class."

The Court's decision in Pollock was unpopular, but it effectively prevented Congress from implementing another income tax over the next two decades since the apportionment requirements were widely regarded as unworkable. The ratification of the Sixteenth Amendment essentially overturned the key holding in Pollock, and Congress established a new federal income tax in the Revenue Act of 1913. The Court's holding regarding the taxation of interest income on certain bonds was later overruled in the 1988 case of South Carolina v. Baker.