Personal Income Tax Introduced in U.S. (1913): At first, income taxes were considered a temporary tax to help raise money for war. The first time an income tax was enacted was in 1799 in Great Britain to help the British pay for troops and supplies to defeat the French forces led by Napoleon.
In the War of 1812, the U.S. first considered enacting an income tax, but the war ended before the tax was officially created. Yet, during the American Civil War, the first U.S. income tax was created, but this one was meant only as a temporary measure to help pay for the war. It was repealed in 1872.
By the 1890s, the U.S. government was hoping to find a way to more evenly distribute the federal tax burden and thus looked at creating a permanent income tax. However, until the 16th Amendment to the Constitution was ratified n 1913, the federal government was forced to collect taxes based on state population.
Once the 16th Amendment was passed, the U.S. government passed its first, permanent income tax law in October 1913.
See the full article: The History of Income Tax in the U.S.