October 15 – Electing Large Partnerships
File a 2014 calendar year return (Form 1065-B). This due date applies only if you were given an additional 6-month extension. March 16 was the due date for furnishing Schedules K-1 or substitute Schedule K-1 to the partners.
October 15 – Social Security, Medicare and withheld income tax
If the monthly deposit rule applies, deposit the tax for payments in September.
October 15 – Nonpayroll Withholding