Supplementary Provisions, Article 5, paragraph (2)
第二項
If a Reassessment under Article 24 or Article 26 of the Act on General Rules for National Taxes has been made based on a request for Reassessment referred to in the preceding paragraph, and interest on refund prescribed in Article 58, paragraph (1) (Interest on Refund) of the Act on General Rules for National Taxes is calculated on a refund under Article 159, paragraph (2) (Refunding Taxes Withheld, Based on Reassessment or Determination) of the new Act (including as applied mutatis mutandis under Article 168 (Application Mutatis Mutandis to Nonresidents) of the new Act), the period under that paragraph that forms the basis of that calculation is the period from the effective date until the day on which the decision to pay for that refund is made or the day on which that refund is subject to Appropriation under Article 57, paragraph (1) (Appropriation) of that Act (or, if there is a day before that day on which the Appropriation became possible, that day).
前項の更正の請求に基づく国税通則法第二十四条又は第二十六条の規定による更正があつた場合において、新法第百五十九条第二項（更正又は決定による源泉徴収税額等の還付）（新法第百六十八条（非居住者に対する準用）において準用する場合を含む。）の規定による還付金について国税通則法第五十八条第一項（還付加算金）に規定する還付加算金を計算するときは、その計算の基礎となる同項の期間は、施行日からその還付のための支払決定をする日又はその還付金につき同法第五十七条第一項（充当）の規定による充当をする日（同日前にその充当をするのに適することとなつた日がある場合には、その適することとなつた日）までの期間とする。