Form 4868 is used to file a request for an extension on or before April 15th of the current tax year to get a four-month extension with your form 1040, 1040A, or 1040 EZ. You have to send in at least 90% of the estimated tax due in order to not incur any late payment penalties by the end of the extension. After you have filed your tax return, you will then be responsible for paying the remainder of the taxes that you owe.
Interest is usually charged on the amount of the unpaid tax from the due date of the return. If the initial four-month extension does not allot you enough time in which to complete your tax return, you may opt to request a further two-month extension from the IRS.
Conditions under which you automatically qualify for the extension without filing the Form 4868 are the following: