A tax extension filed with the IRS provides a tax payer additional time to file their return not pay their taxes. With that said, making your payment to the IRS at the same time as you file your extension is not a requirement. If you are unable to pay your bill you can still apply for the extension.
Since this does not extend the time to pay, can I get additional time?
April 15th is the deadline to pay your tax bill. If you do not pay the amount due by this date, you may owe interest and/or penalties. Under most circumstances the IRS is not willing to postpone this date.
Why do I need to file an extension if it does not give me any more time to pay?
As was mentioned above, you are not required to make a payment in order to file an extension (although it is suggested). The reason you always want to file your return or extension, even if you cannot pay, is the penalty is far greater if you do file anything. The penalty for failing to file a tax return or extension is 5 percent of the outstanding unpaid taxes. In comparison if you file for extension but fail to pay the penalty is ½ percent versus 5.