26 U.S.C. § 2032

(a) General The value of the gross estate may be determined, if the executor so elects, by valuing all the property included in the gross estate as follows: (1) In the case of property distributed, sold, exchanged, or otherwise disposed of, within 6 months after the decedent’s death such property shall be valued as of the date of distribution, sale, exchange, or other disposition. (2) In the case of property not distributed, sold, exchanged, or otherwise disposed of, within 6 months after the decedent’s death such property shall be valued as of the date 6 months after the decedent’s death. (3) Any interest or estate which is affected by mere lapse of time shall be included at its value as of the time of death (instead of the later date) with adjustment for any difference in its value as of the later date not due to mere lapse of time. (b) Special rules No deduction under this chapter of any item shall be allowed if allowance for such items is in effect given by the alternate valuation provided by this section. Wherever in any other subsection or section of this chapter reference is made to the value of property at the time of the decedent’s death, such reference shall be deemed to refer to the value of such property used in determining the value of the gross estate. In case of an election made by the executor under this section, then— (1) for purposes of the charitable deduction under section 2055 or 2106(a)(2), any bequest, legacy, devise, or transfer enumerated therein, and (2) for the purpose of the marital deduction under section 2056, any interest in property passing to the surviving spouse, shall be valued as of the date of the decedent’s death with adjustment for any difference in value (not due to mere lapse of time or the occurrence or nonoccurrence of a contingency) of the property as of the date 6 months after the decedent’s death (substituting, in the case of property distributed by the executor or trustee, or sold, exchanged, or otherwise disposed of, during such 6-month period, the date thereof). (c) Election must decrease gross estate and estate tax No election may be made under this section with respect to an estate unless such election will decrease— (1) the value of the gross estate, and (2) the sum of the tax imposed by this chapter and the tax imposed by chapter 13 with respect to property includible in the decedent’s gross estate (reduced by credits allowable against such taxes). (d) Election (1) In general The election provided for in this section shall be made by the executor on the return of the tax imposed by this chapter. Such election, once made, shall be irrevocable. (2) Exception No election may be made under this section if such return is filed more than 1 year after the time prescribed by law (including extensions) for filing such return.