26 U.S.C. § 6163: Extension of time for payment of estate tax on value of reversionary or remainder interest in property

If the value of a reversionary or remainder interest in property is included under chapter 11 in the value of the gross estate, the payment of the part of the tax under chapter 11 attributable to such interest may, at the election of the executor, be postponed until 6 months after the termination of the precedent interest or interests in the property, under such regulations as the Secretary may prescribe. At the expiration of the period of postponement provided for in subsection (a), the Secretary may, for reasonable cause, extend the time for payment for a reasonable period or periods not in excess of 3 years from the expiration of the period of postponement provided in subsection (a). For authority of the Secretary to require security in the case of an extension under this section, see section 6165. The amendment made by subsection (a) [amending this section] shall apply in the case of any reversionary or remainder interest only if the time for payment of the tax under chapter 11 of the Internal Revenue Code of 1986 [formerly I.R.C. 1954] attributable to such interest, including any extensions thereof, has not expired on the date of the enactment of this Act [ Feb. 26, 1964 ]. The amendment made by subsection (b) [amending section 925 of I.R.C. 1939] shall apply in the case of any reversionary or remainder interest only if the time for payment of the tax under chapter 3 of the Internal Revenue Code of 1939 attributable to such interest, including any extensions thereof, has not expired on the date of the enactment of this Act [ Feb. 26, 1964 ].”