October 11

 
Employees who work for tips – If you received $20 or more in tips during September, report them to your employer. You can use Form 4070.

October 17

 
Individuals – If you have an automatic 6-month extension to file your income tax return for 2015, file Form 1040, 1040A, or 1040EZ and pay any tax, interest, and penalties due.

Electing Large Partnerships – File a 2015 calendar year return (Form 1065-B). This due date applies only if you timely requested a 6-month extension of time to file the return.

Employers Nonpayroll Withholding – If the monthly deposit rule applies, deposit the tax for payments in September.

Employers Social Security, Medicare, and Withheld income tax – If the monthly deposit rule applies, deposit the tax for payments in September.

October 31

 
Employers – Social Security, Medicare, and withheld income tax – File form 941 for the third quarter of 2016. Deposit any undeposited tax. (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 10 to file the return.

Certain Small Employers – Deposit any undeposited tax if your tax liability is $2,500 or more for 2016 but less than $2,500 for the third quarter.

Employers – Federal Unemployment Tax. Deposit the tax owed through September if more than $500.