The 16th Amendment to the US constitution legalized what form of tax?

Income tax.

The 16th Amendment to the United States Constitution, ratified on February 3, 1913, legalized the federal income tax. This amendment granted Congress the power to levy taxes on income from any source without apportioning it among the states based on population. Before its passage, direct taxes had to be distributed among the states according to their population, making it difficult for the federal government to implement an income tax.

The push for an income tax arose primarily from concerns about economic inequality and the limitations of tariff-based revenue. Before the 16th Amendment, the federal government relied heavily on tariffs (taxes on imports) and excise taxes (taxes on specific goods like alcohol and tobacco) for revenue. However, tariffs disproportionately impacted the working class, as they raised the prices of goods. Meanwhile, wealthier individuals often had ways to shield their income from taxation.

The idea of an income tax had been debated for years. In 1894, Congress attempted to impose an income tax through the Wilson-Gorman Tariff Act, but the Supreme Court, in Pollock v. Farmers’ Loan & Trust Co. (1895), ruled that such a tax was unconstitutional unless it was apportioned among the states. This decision effectively blocked the federal government from taxing income directly.

The 16th Amendment overturned the Pollock decision, giving Congress clear authority to impose an income tax. Shortly after its ratification, the Revenue Act of 1913 introduced a graduated income tax, which taxed higher incomes at higher rates. Over time, the federal income tax became a major source of government revenue, funding programs such as Social Security, Medicare, and national defense.

Today, the federal income tax remains one of the most significant and controversial aspects of the U.S. tax system, shaping debates on economic policy, fairness, and government spending.