- Early in U.S. history, most tax revenue came from excise taxes, tariffs, and customs duties rather than income taxes. Income taxes were introduced in 1913 with the ratification of the 16th Amendment. - The Great Depression led to increased income tax rates throughout the 1930s to boost government revenue amid economic decline. Social Security was also established in 1935 and funded by payroll taxes. - Over time, the IRS modernized and income tax rates and rules continued to change through legislation like the 1986 Tax Reform Act to balance tax burdens and government spending needs.

1. FEDERAL INCOME TAX REPORTING History Of U.S. Income Tax