第三条（確定申告書の記載事項に関する経過措置）
Supplementary Provisions, Article 3Transitional Measures Regarding Matters to Be Entered in a Tax Return
The provisions of Article 47, paragraphs (1) and (2), and paragraph (3) (limited to the part relating to item (xxi)), and Article 48, paragraph (2) of the Regulation for Enforcement of the Income Tax Act after amendment (hereinafter referred to as the "New Regulation") apply to cases where a Tax Return for income tax for the year 2025 or any subsequent year is submitted on or after December 1, 2025, and the provisions then in force continue to govern cases where a Tax Return is submitted before that date and cases where a Tax Return for income tax for the year 2024 or any earlier year is submitted on or after that date.
With respect to the application of Articles 47 and 48 of the New Regulation during the period from December 1, 2025 to December 31, 2025, the phrase "基礎並びに" (basis and, joining a larger group) in Article 47, paragraph (1) of the New Regulation is deemed to be replaced with "基礎及び" (basis and, joining a smaller group), the phrase "and item (xxiv) set forth in" in that paragraph is deemed to be replaced with "set forth in", and the phrase "and item (xxiv) set forth in" in Article 48, paragraph (2) of the New Regulation is deemed to be replaced with "set forth in".
令和七年十二月一日から同年十二月三十一日までの間における新規則第四十七条及び第四十八条の規定の適用については、新規則第四十七条第一項中「基礎並びに」とあるのは「基礎及び」と、「及び第二十四号に掲げる」とあるのは「に掲げる」と、新規則第四十八条第二項中「及び第二十四号に掲げる」とあるのは「に掲げる」とする。
略称規定附則第三条第一項
改正後の所得税法施行規則（以下「新規則」という。）第四十七条第一項、第二項及び第三項（第二十一号に係る部分に限る。）並びに第四十八条第二項の規定は、令和七年十二月一日以後に同年分以後の所得税に係る確定申告書を提出する場合について適用し…
わかりやすく言うと
令和七年財務省令第十八号によって改正された後の所得税法施行規則のことです。