26 U.S.C. § 6046 : US Code - Section 6046: Returns as to organization or reorganization of foreign corporations and as to acquisitions of their stock

    (a) Requirement of return
      (1) In general
        A return complying with the requirements of subsection (b)
      shall be made by - 
          (A) each United States citizen or resident who becomes an
        officer or director of a foreign corporation if a United States
        person (as defined in section 7701(a)(30)) meets the stock
        ownership requirements of paragraph (2) with respect to such
        corporation,
          (B) each United States person - 
            (i) who acquires stock which, when added to any stock owned
          on the date of such acquisition, meets the stock ownership
          requirements of paragraph (2) with respect to a foreign
          corporation, or
            (ii) who acquires stock which, without regard to stock
          owned on the date of such acquisition, meets the stock
          ownership requirements of paragraph (2) with respect to a
          foreign corporation,

          (C) each person (not described in subparagraph (B)) who is
        treated as a United States shareholder under section 953(c)
        with respect to a foreign corporation, and
          (D) each person who becomes a United States person while
        meeting the stock ownership requirements of paragraph (2) with
        respect to stock of a foreign corporation.

      In the case of a foreign corporation with respect to which any
      person is treated as a United States shareholder under section
      953(c), subparagraph (A) shall be treated as including a
      reference to each United States person who is an officer or
      director of such corporation.
      (2) Stock ownership requirements
        A person meets the stock ownership requirements of this
      paragraph with respect to any corporation if such person owns 10
      percent or more of - 
          (A) the total combined voting power of all classes of stock
        of such corporation entitled to vote, or
          (B) the total value of the stock of such corporation.
    (b) Form and contents of returns
      The returns required by subsection (a) shall be in such form and
    shall set forth, in respect of the foreign corporation, such
    information as the Secretary prescribes by forms or regulations as
    necessary for carrying out the provisions of the income tax laws,
    except that in the case of persons described only in subsection
    (a)(1)(A) the information required shall be limited to the names
    and addresses of persons described in subparagraph (B) or (C) of
    subsection (a)(1).
    (c) Ownership of stock
      For purposes of subsection (a), stock owned directly or
    indirectly by a person (including, in the case of an individual,
    stock owned by members of his family) shall be taken into account.
    For purposes of the preceding sentence, the family of an individual
    shall be considered as including only his brothers and sisters
    (whether by the whole or half blood), spouse, ancestors, and lineal
    descendants.
    (d) Time for filing
      Any return required by subsection (a) shall be filed on or before
    the 90th day after the day on which, under any provision of
    subsection (a), the United States citizen, resident, or person
    becomes liable to file such return (or on or before such later day
    as the Secretary may by forms or regulations prescribe).
    (e) Limitation
      No information shall be required to be furnished under this
    section with respect to any foreign corporation unless such
    information was required to be furnished under regulations which
    have been in effect for at least 90 days before the date on which
    the United States citizen, resident, or person becomes liable to
    file a return required under subsection (a).
    (f) Cross reference
          For provisions relating to penalties for violations of this
        section, sections 6679 and 7203.