October 16
Individuals. If you have an automatic six-month extension to file your income tax return for 2016, file Form 1040, 1040A, or 1040EZ and pay any tax, interest, or penalties due.
Corporations. File a 2016 calendar-year income tax return (Form 1120) and pay any tax, interest, and penalties due. This due date applies only if you timely requested an automatic six-month extension.
Employers. For Social Security, Medicare, withheld income tax, and nonpayroll withholding, deposit the tax for payments in September if the monthly rule applies.
October 31
Employers. For Social Security, Medicare, and withheld income tax, file Form 941 for the third quarter of 2017. Deposit any undeposited tax. (If your tax liability is less than $2,500, you can pay it in full with a timely filed return.) If you deposited the tax for the quarter in full and on time, you have until November 13 to file the return.
For federal unemployment tax, deposit the tax owed through September if more than $500.
November 13
Employers. For Social Security, Medicare, and withheld income tax, file Form 941 for the third quarter of 2017. This due date applies only if you deposited the tax for the quarter in full and on time.
November 15
Employers. For Social Security, Medicare, withheld income tax, and nonpayroll withholding, deposit the tax for payments in October if the monthly rule applies.
Annual exempt organization return. File a 2016 calendar year Not-For-Profit return (Form 990) by November 15. This due date applies only if you timely requested an automatic six-month extension.