26 U.S.C. § 2032: Alternate valuation

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. 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. 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. for purposes of the charitable deduction under section 2055 or 2106(a)(2), any bequest, legacy, devise, or transfer enumerated therein, and for the purpose of the marital deduction under section 2056, any interest in property passing to the surviving spouse, the value of the gross estate, and 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). 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. 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. The amendment made by subsection (a) [amending this section] shall apply to estates of decedents dying after the date of the enactment of this Act [ July 18, 1984 ]. a credit or refund of the tax imposed by chapter 11 of the Internal Revenue Code of 1986 [formerly I.R.C. 1954] is not prevented on the date of the enactment of this Act by the operation of any law or rule of law, the election under section 2032 of the Internal Revenue Code of 1986 would have met the requirements of such section (as amended by this section and section 1023) had the decedent died after the date of enactment of this Act, and a claim for credit or refund of such tax with respect to such estate is filed not later than the 90th day after the date of the enactment of this Act,