1867 - Congress cuts tax rate. From 1868 until 1913, 90 percent of all revenue comes from taxes on liquor, beer, wine and tobacco.
1872 - Income tax repealed.
1894 - The Wilson Tariff Act revives the income tax, creating the Bureau of Internal Revenue.
1895 - Supreme Court rules new income tax unconstitutional on the grounds it was a direct tax not apportioned among states on the basis of population. Income tax division is disbanded.
1909 - President Taft recommends a constitutional amendment giving the government power to tax incomes without apportioning the burden among states in line with population.
1913 - The 16th amendment is ratified, giveing Congress the power to collect taxes. Form 1040 introduced.
1918 - The Revenue Act of 1918 raises greater sums for World War I effort. It codifies existing tax laws and imposes a progressive income-tax rate structure of up to 77 percent.
1942 - The Revenue Act of 1942 increases taxes and the number of Americans subject to the income tax. It also creates deductions for medical and investment expenses.
1943 - Congress passes act requiring employers to withhold taxes from employees' wages and remit them quarterly.
1944 - Individual Income Tax Act passes. Creates the standard deductions on Form 1040.
1954 - The filing deadline for individual tax returns changes from March 15 to April 15.
1986 - Limited electronic filing begins.
1992 - Taxpayers who owe money allowed to file returns electronically.
Source: Internal Revenue Service
The 16th Amendment giving Congress the power to collect taxes on income passed in 1913, establishing the grid of lines, boxes and arcane instructions endured since 1914.