To request a federal tax extension, file Form 4868. The form is relatively easy to fill out. It asks for name, address and Social Security number for yourself and a spouse, if applicable.
The most difficult part of the form likely will be estimating the taxes you owe, but you have to do it. There are plenty of online calculators to help you estimate your tax liability. If you don't have a sense of total income and exemptions for this year, you can try to estimate based on your prior year's tax returns. If you made 10 percent more this year, adjust the numbers upward by 10 percent.
You can file your federal extension online through Free File on IRS.gov or mail a paper copy to the IRS according to where you live. More than 62 million taxpayers filed taxes electronically in 2014, and the IRS encourages taxpayers to use the web as fast and easy option.
If you owe a payment, you can pay electronically through the Electronic Federal Tax Payment System. You can also make a direct payment through your checking or savings account, or by using a debit card or credit card. In fact, you don't need to file Form 4868 at all if you make any type of electronic payment. The IRS automatically grants an extension if you pay online or by phone [source: IRS].
Tax software programs can also help with payment processing. If you prefer, you can send a check or money order to the federal or state treasury along with a paper copy of Form 4868 [source: IRS]. Any refund you might be expecting will be processed by the IRS after you file your actual returns.
For a state tax extension, look to your state website to find the appropriate tax form. You can start with the IRS State Tax Extension Information site. If you're using tax preparation software, it should include instructions on how to file both state and federal extensions through the software provider.
After the extension has been mailed, it's automatically applied. That means you can assume it was received, and you won't receive notice from the IRS. Then file your returns as you normally would, on or before the Oct. 15 deadline. You don't have to include another copy of the Form 4868 when you file your return.