then section 2107(b) requires the inclusion in the decedent's gross estate, in addition to amounts otherwise includible therein under subdivision (i) of this subparagraph, of an amount equal to that proportion of the fair market value (determined at the time of the decedent's death or, if so elected by the executor of the decedent's estate, on the alternate valuation date as provided in section 2032) of the stock in such foreign corporation owned (within the meaning of section 958(a) and the regulations thereunder) by the decedent at the time of his death, which the fair market value of any assets owned by such foreign corporation and situated in the United States, at the time of his death, bears to the total fair market value of all assets owned by such foreign corporation at the time of his death.
Section 301(b) of the Immigration and Nationality Act provides generally that a U.S. citizen, who is born outside the United States of parents one of whom is an alien and the other is a U.S. citizen who was physically present in the United States for a specified period, shall lose his U.S. citizenship if, within a specified period preceding the age of 28 years, he fails to be continuously physically present in the United States for at least 5 years. Section 350 of that Act provides that under certain circumstances a person, who at birth acquired the nationality of the United States and of a foreign country and who has voluntarily sought or claimed benefits of the nationality of any foreign country, shall lose his U.S. nationality if, after attaining the age of 22 years, he has a continuous residence for 3 years in the foreign country of which he is a national by birth. Section 355 of that Act provides that a person having U.S. nationality, who is under 21 years of age and whose residence is in a foreign country with or under the legal custody of a parent who loses his U.S. nationality under specified circumstances, shall lose his U.S. nationality if he has or acquires the nationality of that foreign country and attains the age of 25 years without having established his residence in the United States. Section 2107 and this section do not apply to the transfer of any estate the estate tax treatment of which is subject to a Presidential proclamation made pursuant to section 2108(a) (relating to the application of pre-1967 estate tax provisions in the case of a foreign country which imposes a more burdensome tax than the United States).
26 C.F.R. §20.2107-1