Corporations: File calendar year Form 1120 if you timely requested a 6-month extension. Calendar Add to Calendar Add to Timely Calendar Add to Google Add to Outlook Add to Apple Calendar Add to other calendar Export to XML When: October 15, 2018 all-day 2018-10-15T00:00:00-07:00 2018-10-16T00:00:00-07:00 ← Deposit payroll tax for payments on Apr 11-13 if the semiweekly deposit rule applies.Deposit payroll tax for payments on Jan. 1-2 if the semiweekly deposit rule applies. →