# Changes to Japanese law on 1 December 2026

This is the Markdown twin of https://japanlaw.org/en/changes/2026-12-01. 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.

What changes on 1 December 2026 in 7 laws on this site: for each, the Act that amends it and the wording before and after, in Japanese and English.

- Whistleblower Protection Act (公益通報者保護法) — https://japanlaw.org/en/whistleblower-protection-act
  - Amended by Act Partially Amending the Whistleblower Protection Act (Act No. 62 of 2025) (公益通報者保護法の一部を改正する法律)
    The Act, and every law here it amends: https://japanlaw.org/en/acts/507AC0000000062 (as Markdown: https://japanlaw.org/md/en/acts/507AC0000000062)
    What changes: https://japanlaw.org/en/whistleblower-protection-act/amendments/20261201_507AC0000000062; the law as amended, in Markdown: https://japanlaw.org/md/en/whistleblower-protection-act/amendments/20261201_507AC0000000062/text
- Employees' Pension Insurance Act (厚生年金保険法) — https://japanlaw.org/en/employees-pension-insurance-act
  - Amended by Act Partially Amending the National Pension Act, etc., and Other Matters, to Strengthen the Functions of the Pension System in Light of Socioeconomic Changes (Act No. 74 of 2025) (社会経済の変化を踏まえた年金制度の機能強化のための国民年金法等の一部を改正する等の法律)
    The Act, and every law here it amends: https://japanlaw.org/en/acts/507AC0000000074 (as Markdown: https://japanlaw.org/md/en/acts/507AC0000000074)
    What changes: https://japanlaw.org/en/employees-pension-insurance-act/amendments/20261201_507AC0000000074; the law as amended, in Markdown: https://japanlaw.org/md/en/employees-pension-insurance-act/amendments/20261201_507AC0000000074/text
- Income Tax Act (所得税法) — https://japanlaw.org/en/income-tax-act
  - Amended by Act Partially Amending the Income Tax Act, etc. (Act No. 12 of 2026) (所得税法等の一部を改正する法律)
    The Act, and every law here it amends: https://japanlaw.org/en/acts/508AC0000000012 (as Markdown: https://japanlaw.org/md/en/acts/508AC0000000012)
    What changes: https://japanlaw.org/en/income-tax-act/amendments/20261201_508AC0000000012; the law as amended, in Markdown: https://japanlaw.org/md/en/income-tax-act/amendments/20261201_508AC0000000012/text
- Regulation for Enforcement of the Income Tax Act (所得税法施行規則) — https://japanlaw.org/en/income-tax-act-enforcement-regulation
  - Amended by Ministerial Order Partially Amending the Regulation for Enforcement of the Income Tax Act (Ministry of Finance Order No. 17 of 2026) (所得税法施行規則の一部を改正する省令)
    The Act, and every law here it amends: https://japanlaw.org/en/acts/508M60000040017 (as Markdown: https://japanlaw.org/md/en/acts/508M60000040017)
    What changes: https://japanlaw.org/en/income-tax-act-enforcement-regulation/amendments/20261201_508M60000040017; the law as amended, in Markdown: https://japanlaw.org/md/en/income-tax-act-enforcement-regulation/amendments/20261201_508M60000040017/text
- Act on Special Measures for Securing the Financial Resources Necessary to Implement Measures for Reconstruction following the Great East Japan Earthquake (東日本大震災からの復興のための施策を実施するために必要な財源の確保に関する特別措置法) — https://japanlaw.org/en/reconstruction-funding-act
  - Amended by Act Partially Amending the Income Tax Act, etc. (Act No. 12 of 2026) (所得税法等の一部を改正する法律)
    The Act, and every law here it amends: https://japanlaw.org/en/acts/508AC0000000012 (as Markdown: https://japanlaw.org/md/en/acts/508AC0000000012)
    What changes: https://japanlaw.org/en/reconstruction-funding-act/amendments/20261201_508AC0000000012; the law as amended, in Markdown: https://japanlaw.org/md/en/reconstruction-funding-act/amendments/20261201_508AC0000000012/text
- Defined Contribution Pension Act (確定拠出年金法) — https://japanlaw.org/en/defined-contribution-pension-act
  - Amended by Act Partially Amending the National Pension Act, etc., and Other Matters, to Strengthen the Functions of the Pension System in Light of Socioeconomic Changes (Act No. 74 of 2025) (社会経済の変化を踏まえた年金制度の機能強化のための国民年金法等の一部を改正する等の法律)
    The Act, and every law here it amends: https://japanlaw.org/en/acts/507AC0000000074 (as Markdown: https://japanlaw.org/md/en/acts/507AC0000000074)
    What changes: https://japanlaw.org/en/defined-contribution-pension-act/amendments/20261201_507AC0000000074; the law as amended, in Markdown: https://japanlaw.org/md/en/defined-contribution-pension-act/amendments/20261201_507AC0000000074/text
- Act on Special Measures Concerning Taxation (租税特別措置法) — https://japanlaw.org/en/special-taxation-measures-act
  - Amended by Act Partially Amending the Income Tax Act, etc. (Act No. 12 of 2026) (所得税法等の一部を改正する法律)
    The Act, and every law here it amends: https://japanlaw.org/en/acts/508AC0000000012 (as Markdown: https://japanlaw.org/md/en/acts/508AC0000000012)
    What changes: https://japanlaw.org/en/special-taxation-measures-act/amendments/20261201_508AC0000000012; the law as amended, in Markdown: https://japanlaw.org/md/en/special-taxation-measures-act/amendments/20261201_508AC0000000012/text

Every day: https://japanlaw.org/en/changes

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## Sources

- Amendments and their dates: e-Gov (Digital Agency) (7 records)
- English names of the laws: Japanese Law Translation, Ministry of Justice (6 records)
- English names of the laws: Written for this site with AI
- English titles of the amending laws: Written for this site with AI