01 Oct October 15
Individuals: If you have an automatic six-month extension to file your income tax return for 2017, file IRS Form 1040, 1040A, or 1040EZ and pay any tax, interest, and penalties due.
Employers: For Social Security, Medicare, withheld income tax, and non-payroll withholding, deposit the tax for payments in September if the monthly rule applies.
Corporations: File a 2017 calendar-year income tax return (IRS Form 1120) and pay any tax, interest, and penalties due. This due date applies only if you timely requested an automatic six-month extension.