Page 1 of the original IRS 1040 income tax form from 1913 appears below. There were only four pages in the original 1040 form, including two pages of worksheets, the actual 1040 form above, and only one page of instructions, view all four pages here. In contrast, just the current 1040 instructions, without any forms, runs 175 pages.
Individual income tax rates started at 1% in 1913, and the maximum marginal income tax rate was only 6% on incomes above $500,000 ($11 million in today’s dollars). The personal exemption was $3,000 for individuals ($66,000 in today’s dollars) and $4,000 for married couples ($87,500 in today’s dollars), meaning that very few Americans had to pay federal income tax since the average income in 1913 was only about $750.