Employers - Social Security, Medicare and withheld income tax. File Form 941 for the third quarter of 2011. 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 2011 but less than $2,500 for the third quarter.

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

Employers - Income Tax Withholding. Ask employees whose withholding allowances will be different in 2010 to fill out a new Form W-4.

Employers - Earned Income Credit. Ask each eligible employee who wants to receive advance payments of earned income credit during the year 2011 to fill out a Form w-5. A new form W-5 must be filled out each year before payments are made.

Employers - Social Security, Medicare and withheld income tax. File Form 941 for the third quarter of 2011. This due date applies only if you deposited the tax for the quarter in full and on time.

Employees - who work for tips. If you received $20 or more in tips during October, report them to your employer. You can use Form 4070 Employee's Report of Tips to Employer.