"In 1913, Wyoming ratified the 16th Amendment, providing the three-quarter majority of states necessary to amend the Constitution. The 16th Amendment gave Congress the authority to enact an income tax. That same year, the first Form 1040 appeared after Congress levied a 1 percent tax on net personal incomes above $3,000 with a 6 percent surtax on incomes of more than $500,000.
In 1918, during World War I, the top rate of the income tax rose to 77 percent to help finance the war effort. It dropped sharply in the post-war years, down to 24 percent in 1929, and rose again during the Depression. During World War II, Congress introduced payroll withholding and quarterly tax payments."
From: "Brief History of IRS", Internal Revenue Service, last modified March 8, 2011, http://www.irs.gov/irs/article/0,,id=149200,00.html.
Therefore, my Great-grandfather, Moritz Beyer, may have had to file a 1913 Form 1040 income tax return. If so, the filing deadline was March 1, 1914.