There are a variety of IRS deadlines which impact Taxpayers, below is a list of some of the notable deadlines. Note: when a deadline falls on a weekend or a legal holiday, it is typically postponed until the next business day. The following deadlines represent the date assuming it does not fall on a weekend or holiday.
February 15
Exemption from income tax withholding (W-4)
April 15
Income tax and self-employment tax return (1040, 1040A, and 1040EZ)
Application for automatic six-month extension (4868) to file income tax return
October 15
Income tax return for taxpayers who obtained a six-month extension (4868)
April 15
Fiduciary income tax return (1041)
Application for automatic five-month extension (7004) to file income tax return
September 15
Form 1041 for estates or trusts that obtained automatic five-month extension
March 15
Income tax return (1120)
Application by calendar-year corporations for automatic six-month extension (7004)
[For S-Corps] Copy of Schedule K-1 to each shareholder
[For S-Corps] Election to be treated as S corporation (2553)
September 15
Form 1120 for corporations that obtained an automatic six-month extension
March 15
Annual information return (990) for organizations exempt under code section 501 or code section 4947(a)(1)
Extension of time (8868) to file 990
January 31
Employee statement (W-2) for tax withheld
Form 943 for income and FICA taxes withheld by employers of agricultural workers
Form 940 for FUTA taxes