In order to elect portability of the decedent's unused exclusion amount (deceased spousal unused exclusion (DSUE) amount) for the benefit of the surviving spouse, the estate's representative must file an estate tax return (Form 706) and the return must be filed timely. The due date of the estate tax return is nine months after the decedent's date of death, however, the estate's representative may request an extension of time to file the return for up to six months. An automatic six month extension of time to file the return is available to all estates, including those filing solely to elect portability, by filing Form 4768 on or before the due date of the estate tax return.
If the estate representative did not file an estate tax return within nine months after the decedent's date of death, or within fifteen months of the decedent's date of death (if a six month extension of time for filing the estate tax return had been obtained), the availability of a further extension of time to elect portability of the DSUE amount depends on whether the estate has a filing requirement, based on the filing threshold.
If the filing threshold has not been met (in other words; but for the need to make the portability election, the estate would not be required to file an estate tax return) Revenue Procedure 2017-34 PDF provides a simplified method for certain taxpayers to obtain an extension of time to make the “portability” election under § 2010(c)(5)(A) of the Internal Revenue Code. The simplified method provided in Revenue Procedure 2017-34 is used in lieu of the letter ruling process.
If the filing threshold has been met, or in other words, if independent of the portability election the estate would otherwise be required to file an estate tax return, then in that case no extension of time to elect portability is available through Revenue Procedure 2017-34.
See also: Portability of the Estate Tax Exemption