Tax forms in the United States are used by taxpayers and tax-exempt organizations to report financial information to the Internal Revenue Service (IRS). They are used to report income and calculate taxes owed to the government of the United States.
 

1040
The Form 1040, U.S. Individual Income Tax Return, is the starting form for personal (individual) Federal income tax returns filed with the Internal Revenue Service (IRS) in the United States. The first Form 1040 was published for use for the tax years 1913, 1914, and 1915. Beginning with the tax year 1916, Form 1040 was converted to an annual form (i.e., updated each tax year with the new year printed on the form).
 

Any full-time resident individual U.S. income taxpayer can use Form 1040 (often referred to as the "long form" to distinguish it from the other 1040 variants). Those with uncomplicated tax situations (for example, no itemized deductions, no capital gain or loss, etc.) may be able to use the simplified Form 1040A (the "short form") or the even simpler Form 1040EZ (the "easy form") instead of Form 1040. Some versions of Form 1040 are colored blue (though not the case when tax return software packages are used).
 

Income tax returns for individual calendar year taxpayers are due by April 15 of the next year. Should April 15 fall on a Saturday, Sunday, or holiday, the returns are due on the first succeeding day that is not a Saturday, Sunday, or holiday. If Patriots Day (a state holiday in Massachusetts) falls on the Monday in question, then filers in southern New England and some parts of New York State have until Tuesday to file, since the IRS processing center for these areas is located in Andover, Massachusetts. Generally, income tax returns for fiscal year taxpayers (an individual taxpayer may choose a fiscal year other than the calendar year, though this is uncommon) are due on or before the 15th day of the fourth month following the close of the fiscal year (if the 15th falls on a Saturday, Sunday, or holiday, the return must be filed by the next business day).
 

Form 1040 consists of two full pages not counting attachments. The first page collects information about the taxpayer(s), dependents, income items, and adjustments to income. The second page calculates the allowable deductions and credits, tax due given the income figure, and applies funds already withheld from wages or estimated payments made towards the tax liability.

Form 1040 has 11 attachments, called "schedules" (Schedules A and B are printed opposite sides of the same sheet) which may need to be filed depending on the taxpayer:
 

Schedule A itemizes allowable deductions against income; instead of filling out Schedule A, taxpayers may choose to take a standard deduction of between $5,150 and $14,300, depending on age, filing status, and whether the taxpayer and/or spouse is blind.

In most situations, other Internal Revenue Service or Social Security Administration forms such as Form W-2 must be attached to the Form 1040, in addition to the Form 1040 schedules. There are other, specialized forms which may need to be completed along with Schedules and the Form 1040.
 

A 1040 form appears on the family crest of Brutus Thorndike, the main character of the Born Loser cartoon strip.

United States Internal Revenue Service - includes downloadable forms and publications
The Form 1040 lines that lead to the most mistakes - MarketWatch