Individuals - If you are a U.S. citizen or resident alien living and working (or on military duty) outside the United States and Puerto Rico, file Form 1040 and pay any tax, interest and penalties due. Otherwise, see April 15. If you want additional time to file your return, file Form 4868 to obtain 4 additional months to file. Then file Form 1040 by October 15.

However, if you are a participant in a combat zone you may be able to further extend the filing deadline.

Individuals - Make a payment of your estimated tax for 2008 if you did not pay your income tax for the year throught withholding (or did not pay in enough tax that way). Use Form 1040-ES. This is the final installment date for 2008 estimated tax. However, you do not have to make this payment if you file your 2008 return (Form 1040) and pay any tax due by February 2, 2009.

Corporations - Deposit the second installment of estimated income tax for 2009. A worksheet, Form 1120-W is available to help you estimate your tax for the year.

Employers - Social Security, Medicare and withheld income tax. If the monthly deposit rule applies, deposit the tax for payments in May.

Employers - Nonpayroll withholding. If the monthly deposit rule applies, deposit the tax for payments in May.