Form 1040 is the standard individual income tax return form used by U.S. taxpayers to report their annual income to the Internal Revenue Service (IRS). It allows individuals to calculate their tax liability, claim deductions, and report credits. Taxpayers typically file Form 1040 by April 15 each year, covering income earned in the previous calendar year. The form includes various sections for reporting wages, interest, dividends, and other sources of income, as well as adjustments and tax payments.