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

(出国をする場合の予定納税額の納期限の特例)
第百十五条  第百四条第一項（予定納税額の納付）又は第百七条第一項（特別農業所得者の予定納税額の納付）の規定により予定納税額を納付すべき居住者は、これらの規定に規定する納期限前に出国をする場合には、これらの規定にかかわらず、その出国後に当該納期限の到来する予定納税額に相当する所得税を、その出国の時までに国に納付しなければならない。

Special Provisions on the Deadlines for Making Tax Prepayments If the Taxpayer Will Become Absent From Japan
Article 115  Notwithstanding the provisions of Article 104, paragraph (1) (Making Tax Prepayments) and Article 107, paragraph (1) (Tax Prepayments by Special Farming Income Earners), if a Resident that is required to make a Tax Prepayment pursuant to those provisions will become Absent From Japan prior to the payment deadline prescribed in those provisions, the Resident must pay income taxes to the national government in an amount equivalent to any Tax Prepayment with a deadline falling after the start of the Resident's Absence From Japan, by the start of the Resident's Absence From Japan.