((a)) ** Imposition of more burdensome tax by foreign country** Whenever the President finds that—

((1)) under the laws of any foreign country, considering the tax system of such foreign country, a more burdensome tax is imposed by such foreign country on the transfer of estates of decedents who were citizens of the United States and not residents of such foreign country than the tax imposed by this subchapter on the transfer of estates of decedents who were residents of such foreign country,

((2)) such foreign country, when requested by the United States to do so, has not acted to revise or reduce such tax so that it is no more burdensome than the tax imposed by this subchapter on the transfer of estates of decedents who were residents of such foreign country, and

((3)) it is in the public interest to apply pre-1967 tax provisions in accordance with this section to the transfer of estates of decedents who were residents of such foreign country,

((b)) ** Alleviation of more burdensome tax** Whenever the President finds that the laws of any foreign country with respect to which the President has made a proclamation under subsection (a) have been modified so that the tax on the transfer of estates of decedents who were citizens of the United States and not residents of such foreign country is no longer more burdensome than the tax imposed by this subchapter on the transfer of estates of decedents who were residents of such foreign country, he shall proclaim that the tax on the transfer of the estate of every decedent who was a resident of such foreign country at the time of his death shall, in the case of decedents dying after the date of such proclamation, be determined under this subchapter without regard to subsection (a).

((c)) ** Notification of Congress required** No proclamation shall be issued by the President pursuant to this section unless, at least 30 days prior to such proclamation, he has notified the Senate and the House of Representatives of his intention to issue such proclamation.

((d)) ** Implementation by regulations** The Secretary shall prescribe such regulations as may be necessary or appropriate to implement this section.