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.
December 15
Employers. For Social Security, Medicare, withheld income tax, and nonpayroll withholding, deposit the tax for payments in November if the monthly rule applies.
Corporations. Deposit the fourth installment of estimated income tax for 2017.