# 所得税法 / Income Tax Act — 第一条 (Supplementary Provisions, Article 1) This is the Markdown twin of https://japanlaw.org/ja/income-tax-act/suppl-5031-11/art-1. Every law, and how to address a provision: https://japanlaw.org/llms.txt. The same laws as MCP tools (no sign-in): https://japanlaw.org/mcp. - Law: 所得税法 (Income Tax Act), 昭和四十年法律第三十三号 - English title "Income Tax Act": Ministry of Justice translation - Kind: Act — the distinction between 法律 (Act), 政令 (Cabinet Order), 省令 (Ministerial Order) and 条例 (local ordinance) decides who may issue it and what it may say. - Provision: 第一条 (Supplementary Provisions, Article 1)（施行期日） — address `suppl-5031-11/art-1` - Text in force since: 2026-10-01 - URL (the page that opens at this provision): https://japanlaw.org/ja/income-tax-act/suppl-5031-11/art-1 - e-Gov law ID: 340AC0000000033 — never renamed. A permanent link, `/l/{lawId}/{address}` on this site, redirects to the page. - Every provision below carries its address and its URL on the line under it. - Japanese text: e-Gov 法令検索, Digital Agency (デジタル庁). English: as marked on each line below. Only the Japanese as published by the government has legal effect; the text below is a copy of it. Every English rendering below is a translation and says which kind: the Ministry of Justice's translation, or this site's machine translation, whose model and date the Sources list names. They are never merged and never substituted for one another. --- ### 第一条（施行期日） — Effective Date caption: machine translation, not official suppl-5031-11/art-1 · https://japanlaw.org/ja/income-tax-act/suppl-5031-11/art-1 **第一項** この法律は、令和三年四月一日から施行する。ただし、次の各号に掲げる規定は、当該各号に定める日から施行する。 suppl-5031-11/art-1/par-1 · https://japanlaw.org/ja/income-tax-act/suppl-5031-11/art-1/par-1 This Act comes into effect on April 1, 2021; provided, however, that the provisions set forth in the following items come into effect on the dates specified in those items: machine translation, not official **一から四まで** 略 suppl-5031-11/art-1/par-1/item-1-to-4 · https://japanlaw.org/ja/income-tax-act/suppl-5031-11/art-1/par-1/item-1-to-4 Omitted machine translation, not official **五** 次に掲げる規定　令和四年一月一日 suppl-5031-11/art-1/par-1/item-5 · https://japanlaw.org/ja/income-tax-act/suppl-5031-11/art-1/par-1/item-5 the following provisions: January 1, 2022; machine translation, not official **イ** 第一条の規定（同条中所得税法第九条の改正規定、同法第十条の改正規定、同法第十一条の改正規定、同法第四十五条第一項の改正規定、同法第七十八条第二項第三号の改正規定、同法第百九十六条第一項の改正規定、同法第百九十八条の改正規定、同法第二百三条の改正規定（同条第一項第二号及び第四号に係る部分を除く。）及び同法第二百三条の六の改正規定を除く。）並びに附則第五条、第七条、第九条、第百二十二条、第百二十三条及び第百二十六条（所得税法等の一部を改正する等の法律（平成二十九年法律第四号）附則第七条の改正規定及び同法附則第五十八条の改正規定に限る。）の規定 suppl-5031-11/art-1/par-1/item-5/sub-1 · https://japanlaw.org/ja/income-tax-act/suppl-5031-11/art-1/par-1/item-5/sub-1 the provisions of Article 1 (excluding, among the provisions of that Article, the provision amending Article 9 of the Income Tax Act, the provision amending Article 10 of that Act, the provision amending Article 11 of that Act, the provision amending Article 45, paragraph (1) of that Act, the provision amending Article 78, paragraph (2), item (iii) of that Act, the provision amending Article 196, paragraph (1) of that Act, the provision amending Article 198 of that Act, the provision amending Article 203 of that Act (excluding the parts concerning paragraph (1), items (ii) and (iv) of that Article) and the provision amending Article 203-6 of that Act), and the provisions of Article 5, Article 7, Article 9, Article 122, Article 123 and Article 126 (limited to the provision amending Article 7 of the Supplementary Provisions of the Act Partially Amending the Income Tax Act, etc., and Other Matters (Act No. 4 of 2017) and the provision amending Article 58 of the Supplementary Provisions of that Act) of the Supplementary Provisions; machine translation, not official **六から八まで** 略 suppl-5031-11/art-1/par-1/item-6-to-8 · https://japanlaw.org/ja/income-tax-act/suppl-5031-11/art-1/par-1/item-6-to-8 Omitted machine translation, not official **九** 次に掲げる規定　医薬品、医療機器等の品質、有効性及び安全性の確保等に関する法律等の一部を改正する法律（令和元年法律第六十三号）附則第一条第二号に掲げる規定の施行の日 suppl-5031-11/art-1/par-1/item-9 · https://japanlaw.org/ja/income-tax-act/suppl-5031-11/art-1/par-1/item-9 the following provisions: the date on which the provisions set forth in Article 1, item (ii) of the Supplementary Provisions of the Act Partially Amending the Act on Securing Quality, Efficacy and Safety of Products Including Pharmaceuticals and Medical Devices, etc. (Act No. 63 of 2019) come into effect; machine translation, not official **イ** 第一条中所得税法第四十五条第一項の改正規定 suppl-5031-11/art-1/par-1/item-9/sub-1 · https://japanlaw.org/ja/income-tax-act/suppl-5031-11/art-1/par-1/item-9/sub-1 the provision of Article 1 amending Article 45, paragraph (1) of the Income Tax Act. machine translation, not official --- ## Cites - suppl-5031-11/art-1/par-1/item-5/sub-1: 附則第五条 → 所得税法 附則第五条 (Supplementary Provisions, Article 5), suppl-5031-11/art-5 — https://japanlaw.org/ja/income-tax-act/suppl-5031-11/art-5 - suppl-5031-11/art-1/par-1/item-5/sub-1: 第七条 → 所得税法 附則第七条 (Supplementary Provisions, Article 7), suppl-5031-11/art-7 — https://japanlaw.org/ja/income-tax-act/suppl-5031-11/art-7 - suppl-5031-11/art-1/par-1/item-5/sub-1: 第九条 → 所得税法 附則第九条 (Supplementary Provisions, Article 9), suppl-5031-11/art-9 — https://japanlaw.org/ja/income-tax-act/suppl-5031-11/art-9 ## Cited by 1 provision cites this one. No official source publishes this direction. - 所得税法 附則第百三十一条第一項（罰則に関する経過措置） — https://japanlaw.org/ja/income-tax-act/suppl-5031-11/art-131/par-1 --- ## Sources - e-Gov 法令検索, Digital Agency (デジタル庁) — 所得税法 — the text in force from 2026-10-01 (https://laws.e-gov.go.jp/law/340AC0000000033/20261001_507AC0000000070), retrieved 2026-10-05 - Japanese Law Translation Database System, Ministry of Justice (法務省) — Income Tax Act — Ministry of Justice translation (https://www.japaneselawtranslation.go.jp/en/laws/view/3120/tb), retrieved 2026-09-18 - claude-opus-5[1m] — Machine translation, batch income-tax-act-20260918T180319-130, translated 2026-09-18 - This site's parser, version 225 — 所得税法 — structure, counts, cross-references and defined terms, computed 2026-10-05