What must a surviving spouse file to claim the deceased spousal unused exclusion?

To claim the deceased spousal unused exclusion (DSUE), a surviving spouse must file Form 706, the United States Estate (and Generation-Skipping Transfer) Tax Return. This form is necessary because it allows the executor of the deceased spouse's estate to elect to transfer any unused exclusion amount to the surviving spouse. The DSUE amount enables the surviving spouse to use the deceased spouse's unused estate and gift tax exclusion when they eventually pass away or make significant lifetime gifts, thereby potentially reducing their own estate's tax liability.

Filing Form 706 ensures that the specifics of the deceased spouse's estate and any unused exclusion amounts are officially recorded, allowing the survivor to take advantage of these benefits. The form must be filed within nine months after the date of death, unless an extension is granted. The correct choice reflects this critical requirement in estate planning and tax law. Other forms like Form 1040 and a Gift Tax Return do not serve this specific function of claiming the DSUE, hence they are not suitable options for this scenario.