October 15 – Electing Large Partnerships
File a 2012 calendar year return (Form 1065-B). This due date applies only if you were given an additional 6-month extension. March 15 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
If the monthly deposit rule applies, deposit the tax for payments in September.
October 31 – Social Security, Medicare and Withheld Income Tax
File Form 941 for the third quarter of 2013. Deposit or pay any undeposited tax under the accuracy of deposit rules. If your tax liability is less than $2,500, you can pay it in full with a timely filed return. If you deposited the tax for the quarter in full and on time, you have until November 12 to file the return.
October 31 – Certain Small Employers
Deposit any undeposited tax if your tax liability is $2,500 or more for 2013 but less than $2,500 for the third quarter.
October 31 – Federal Unemployment Tax
Deposit the tax owed through September if more than $500.