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.