Form 4868, a six-month extension of time to file, allows a taxpayer to
◦ avoid interest on underpayment of taxes due.
◦ extend the filing date of the return as well as payment of the tax due.
◦ extend the filing date of the return but the estimated amount of tax due must still be paid by the original due date of the return.
◦ extend the filing date only at the discretion of the IRS.