How much extra time do you get with an IRS extension
Not legal advice: If you file an extension with the IRS on Form 4868, the deadline for filing your tax return is automatically extended to October 15, 2012. The extension must be filed by April 17, 2012.
If you file your return after the due date, including extension, there is typically a 5% penalty on any amount due for each month the return is late, with a maximum penalty of 25%. The extension to file is not an extension to pay. Late payment and interest penalties will be owed on any tax not paid by April 17, 2012, regardless of the extension.
The late payment penalty is incurred each month at a rate of 0.5% of any tax not paid by April 17, 2012. Additionally, interest is applied based on the federal short term interest rate + 3%. a