Before the due date of the return, you may request an extension of time to file your return by writing to the Department of Treasury, Internal Revenue Service Center, Cincinnati, OH 45999-0031. The letter must fully explain the cause of the delay. However, an extension of time to file does not extend the time to pay the tax. A separate request has to be made for the extension of time to make a late payment. For taxpayers abroad, the extension may be for no more than 6 months.