If you pay quarterly estimates, pay the 3rd quarterly estimate by using 1040-ES or logging into the IRS’ website and pay by September 15th.
Deposit 3rd quarter estimates by September 15th using 1120-W.
For calendar-year return, file the Form 1065 by the 15th day of the month if an extension was filed. This only applies to those partnerships that filed for an automatic 6 month extension. Provide each partner with Schedule K-1 after the return has been completed.
File a 2017 calendar-year return (Form 1120-S) by September 15th. This due date only applies if you timely requested an automatic 6-month extension. Provide each shareholder with a copy of Schedule K-1.