September 15, 2017 @ 12:00 am - September 16, 2017 @ 12:00 am Electing Large Partnerships: File Form 1065-B if you timely requested an extension.
September 15, 2017 @ 12:00 am - September 16, 2017 @ 12:00 am Corporations: File calendar year Form 1120 or 1120S if you timely requested a 5 or 6-month extension (see instructions).
September 15, 2017 @ 12:00 am - September 16, 2017 @ 12:00 am Pay the third installment of your 2017 estimated tax – Use Form 1040-ES.
