26 CFR § 1.679-5 - Pre-immigration trusts.
(a) In general. If a nonresident alien individual becomes a U.S. person and the individual has a residency starting date (as determined under section 7701(b)(2)(A)) within 5 years after directly or indirectly transferring property to a foreign trust (the original transfer), the individual is treated as having transferred to the trust on the residency starting date an amount equal to the portion of the trust attributable to the property transferred by the individual in the original transfer.
(b) Special rules -
(1) Change in grantor trust status. For purposes of paragraph (a) of this section, if a nonresident alien individual who is treated as owning any portion of a trust under the provisions of subpart E of part I of subchapter J, chapter 1 of the Internal Revenue Code, subsequently ceases to be so treated, the individual is treated as having made the original transfer to the foreign trust immediately before the trust ceases to be treated as owned by the individual.
(2) Treatment of undistributed income. For purposes of paragraph (a) of this section, the property deemed transferred to the foreign trust on the residency starting date includes undistributed net income, as defined in section 665(a), attributable to the property deemed transferred. Undistributed net income for periods before the individual's residency starting date is taken into account only for purposes of determining the amount of the property deemed transferred.
(c) Examples. The rules of this section are illustrated by the following examples: