January 10 – Employees who work for tips.  If you received $20 or more in tips during December, report them to your employer.  You can use Form 4070, Employee's Report of Tips to Employer.

January 17 – Individuals.  Make a payment of your estimated tax for 2003 if you did not pay your income tax for the year through withholding (or did not pay in enough tax that way).  UseForm 1040–ES.  This is the final installment date for 2005 estimated tax.  However, you do not have to make this payment if you file your 2005 return (Form 1040) and pay any tax due by January 31, 2006.

January 15 – Farmers and fishermen.  Pay your estimated tax for 2005 using Form 1040–ES.  You have until April 15 to file your 2005 income tax return (Form 1040).  If you do not pay your estimated tax by January 15, you must file your 2005 return and pay any tax due by March 1, 2006, to avoid an estimated tax penalty.

January 31 – Individuals who must make estimated tax payments.  If you did not pay your last installment of estimated tax by January 17, you may choose (but are not required) to file your income tax return (Form 1040) for 2005 by January 31.  Filing your return and paying any tax due by January 31 prevents any penalty for late payment of the last installment.  If you cannot file and pay your tax by January 31, file and pay your tax by April 17.

Note.  The 3 months that make up each quarter of a fiscal year may be different from those of each calendar quarter, depending on when the fiscal year begins.

Individuals.  Form 1040.  This form is due on the 15th day of the 4th month after the end of your tax year.

Estimated tax payments (Form 1040–ES).  Payments are due on the 15th day of the 4th, 6th, and 9th months of your tax year and on the 15th day of the 1st month after your tax year ends.