# 所得税法施行令 / Order for Enforcement of the Income Tax Act — 第百六十六条 (Article 166)

This is the Markdown twin of https://japanlaw.org/en/income-tax-act-enforcement-order/art-166. 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: 所得税法施行令 (Order for Enforcement of the Income Tax Act), 昭和四十年政令第九十六号
- English title "Order for Enforcement of the Income Tax Act": Ministry of Justice translation
- Kind: CabinetOrder — 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: 第百六十六条 (Article 166)（事業専従者控除の限度額の計算） — address `art-166`
- Text in force since: 2026-05-22
- URL (the page that opens at this provision): https://japanlaw.org/en/income-tax-act-enforcement-order/art-166
- e-Gov law ID: 340CO0000000096 — 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.

---

### 第百六十六条（事業専従者控除の限度額の計算） — Calculation of Limit of Deduction for a Relative Employed Only in the Business
<sup>caption: machine translation, not official</sup>
<sup>art-166 · https://japanlaw.org/en/income-tax-act-enforcement-order/art-166</sup>

      **第一項**  法第五十七条第三項第二号（事業に専従する親族がある場合の必要経費の特例等）に規定する山林所得の金額は、法第三十二条第三項（山林所得の金額）に規定する残額とする。
      <sup>art-166/par-1 · https://japanlaw.org/en/income-tax-act-enforcement-order/art-166/par-1</sup>
      The amount of timber income prescribed in Article 57, paragraph (3), item (ii) (Special Provisions on Necessary Expenses If Relatives Work Exclusively for a Resident) of the Act is the remainder prescribed in Article 32, paragraph (3) (Amount of Timber Income) of the Act.
      <sup>machine translation, not official</sup>

      **第二項**  居住者が不動産所得、事業所得又は山林所得のうち二以上の所得を生ずべき事業（法第五十七条第三項に規定する事業専従者の従事する事業に限る。）を営む場合における同項第二号の規定の適用については、当該事業に係る同号に規定する不動産所得の金額、事業所得の金額又は山林所得の金額の合計額及び当該事業に従事するすべての当該事業専従者の数を基礎として同号に掲げる金額を計算するものとする。
      <sup>art-166/par-2 · https://japanlaw.org/en/income-tax-act-enforcement-order/art-166/par-2</sup>
      For the application of the provisions of Article 57, paragraph (3), item (ii) of the Act where a Resident carries on a business that is to generate two or more of real property income, business income and timber income (limited to a business in which a relative employed only by the Resident prescribed in paragraph (3) of that Article is engaged), the amount set forth in item (ii) of that paragraph is calculated on the basis of the sum of the amount of real property income, amount of business income or amount of timber income prescribed in item (ii) of that paragraph pertaining to those businesses and the number of all those relatives employed only by the Resident engaged in those businesses.
      <sup>machine translation, not official</sup>

---

## Cites
- art-166/par-1: 法第五十七条第三項第二号 → 所得税法 第五十七条第三項第二号 (Article 57, paragraph (3), item (ii)), art-57/par-3/item-2 — https://japanlaw.org/en/income-tax-act/art-57/par-3/item-2 (e-Gov law ID 340AC0000000033)
- art-166/par-1: 法第三十二条第三項 → 所得税法 第三十二条第三項 (Article 32, paragraph (3)), art-32/par-3 — https://japanlaw.org/en/income-tax-act/art-32/par-3 (e-Gov law ID 340AC0000000033)
- art-166/par-2: 法第五十七条第三項 → 所得税法 第五十七条第三項 (Article 57, paragraph (3)), art-57/par-3 — https://japanlaw.org/en/income-tax-act/art-57/par-3 (e-Gov law ID 340AC0000000033)
- art-166/par-2: 同項第二号 → 所得税法 第五十七条第三項第二号 (Article 57, paragraph (3), item (ii)), art-57/par-3/item-2 — https://japanlaw.org/en/income-tax-act/art-57/par-3/item-2 (e-Gov law ID 340AC0000000033)

---

## Sources

- e-Gov 法令検索, Digital Agency (デジタル庁) — 所得税法施行令 — the text in force from 2026-05-22 (https://laws.e-gov.go.jp/law/340CO0000000096/20260522_508CO0000000093), retrieved 2026-11-06
- Japanese Law Translation Database System, Ministry of Justice (法務省) — Order for Enforcement of the Income Tax Act — Ministry of Justice translation (https://www.japaneselawtranslation.go.jp/en/laws/view/3121/tb), retrieved 2026-11-06
- claude-sonnet-5-5 — Machine translation, batch income-tax-act-enforcement-order-20261106T173921-042, translated 2026-11-07
- claude-sonnet-5-5, corrected on review by claude-opus-5-5 — Machine translation corrected on review, batch income-tax-act-enforcement-order-20261106T173921-042, translated 2026-11-07
- This site's parser, version 229 — 所得税法施行令 — structure, counts, cross-references and defined terms, computed 2026-11-06