法令翻訳 http://www.japaneselawtranslat...ky=&page=3

(年の中途で非居住者が居住者となつた場合の税額の計算)
第百二条  その年十二月三十一日（その年の中途において死亡した場合には、その死亡の日）において居住者である者でその年において非居住者であつた期間を有するもの又はその年の中途において出国をする居住者でその年一月一日からその出国の日までの間に非居住者であつた期間を有するものに対して課する所得税の額は、前二章（課税標準及び税額の計算）の規定により計算した所得税の額によらず、居住者であつた期間内に生じた第七条第一項第一号（居住者の課税所得の範囲）に掲げる所得（非永住者であつた期間がある場合には、当該期間については、同項第二号に掲げる所得）並びに非居住者であつた期間内に生じた第百六十四条第一項各号（非居住者に対する課税の方法）に掲げる非居住者の区分に応ずる同項各号及び同条第二項各号に掲げる国内源泉所得に係る所得を基礎として政令で定めるところにより計算した金額による。

(Calculating the Amount of Taxes If a Nonresident Becomes a Resident Partway Through the Year)
Article 102  Irrespective of the amount of income taxes calculated pursuant to the provisions of the preceding two Chapters (Tax Base and Calculating the Amount of Taxes), the amount of income taxes to be imposed on a person that is a Resident as of December 31 of the relevant year (or as of the date of the person's death, if the person has died partway through the year) but that was a Nonresident for some part of the year; or on a Resident that becomes Absent From Japan partway through the year and that was a Nonresident for some period between January 1 of the relevant year and the date on which the Resident became Absent From Japan, is calculated pursuant to Cabinet Order based on the amount of income set forth in Article 7, paragraph (1), item (i) (Scope of Taxable Income of Residents) that was generated during the period when the person was a Resident (or the amount of income set forth in item (ii) of that paragraph for any period during which the person was a Non-Permanent Resident) and the amount of income categorized as domestic source income set forth in the items of Article 164, paragraph (1) (How Nonresidents Are Taxed) and the items of paragraph (2) of that Article, in accordance with the categories of Nonresidents set forth in the items of paragraph (1) of that Article, which was generated during the period when the person was a Nonresident.