2-13 liability to the Govern- ment of the United States for the tax which, but for this subsection, would otherwise be imposed by the Government of the United States on such income. For purposes of this Section, the term “resident of the Marshall Islands or the Federated States of Micronesia" shall be deemed to include any person who was physically present in the Marshall Islands or the Federated States of Micronesia for a period of 183 or more days during any taxable year; provided, that as between the Governments of the Marshall Islands and the Federated States of Micronesia, the authority to tax an individual resident of the Marshall ~ Islands or the Federated States of Micronesia in respect of income from sources without the Marshall Islands and the Federated States of Micronesia as provided in this subsection may be exercised only by the Government in whose jurisdiction such individual was physically present for the greatest number of days during the taxable year. (b) If the Government of the Marshall Islands or the Federated States of Micronesia subjects income to taxation substan tially similar to that imposed by the Trust Territory Code in effect on January 1, 1980, such Government shall be deemed to have exercised the authority described in Section 254(a). Section 255 Where not otherwise manifestly inconsistent with the intent of this Compact, provisions in the United States Internal Revenue Code that are applicable to possessions of the United States as of January 1, 1980 shall be treated as applying to the Marshall Islands and the Federated States of Micronesia. If such provisions of the Internal Revenue Code are amended, modified or repealed after that date, such provisions shall continue in effect as to the Marshall Islands and the Federated States of Micronesia for a period of two years during which time the Government of the United States and the Governments of the Marshall Islands and the Federated States of Micronesia shall negotiate an agreement which shall provide benefits substantively equivalent to those which obtained under such provisions.