How do you file for an extension on taxes?

Using the Form 4868 you can click on the below related link for more information.

In addition to filing Form 4868 electronically, or by paying part of your tax by credit card, you can file Form 4868 by filling out the form and mailing it to the place where you will file your return.

Please be aware that an extension of time to file is NOT an extension of time to pay.