Japan is moving from voluntary sustainability reporting to phased use of Sustainability Standards Board of Japan standards by large companies listed on the Tokyo Stock Exchange Prime Market.
The timetable is based on average market capitalisation, with the largest companies entering first. Assurance is planned to follow one year after a company’s mandatory reporting begins.
The three SSBJ standards
The SSBJ issued its inaugural standards on March 5, 2025:
- Universal Application of the Sustainability Disclosure Standards.
- General Disclosures.
- Climate-related Disclosures.
Together, the first two address content contained in IFRS S1, while the third corresponds to IFRS S2. The standards were developed to align with the ISSB baseline while reflecting Japanese legal and business circumstances.
Multinational groups should map the SSBJ requirements against their IFRS S1 and IFRS S2 process. A shared data model can reduce duplication, but local reporting, timing, language, and governance still need explicit owners.
Japan’s phased mandatory roadmap
The Financial Services Agency’s January 2026 roadmap phases mandatory disclosure for Prime Market companies using average market capitalisation:
- ¥3 trillion or more: fiscal years ending March 2027.
- ¥1 trillion to less than ¥3 trillion: fiscal years ending March 2028.
- ¥500 billion to less than ¥1 trillion: fiscal years ending March 2029.
- Other Prime Market companies: timing to be determined with further consideration.
Companies should confirm the FSA’s prescribed calculation and reference period rather than relying on a current market-data snapshot. The classification affects both the first mandatory disclosure year and the downstream assurance timetable.
The roadmap also contemplates relief that allows sustainability information to be filed after the annual securities report for a transition period. Treat that as sequencing relief, not extra time to begin building data controls.
Assurance follows mandatory reporting
The FSA roadmap starts assurance one year after the relevant mandatory disclosure date. Limited assurance is planned for the first two years, with an initial scope focused on key items such as Scope 1 and Scope 2 greenhouse gas emissions, governance, risk management, and other specified information.
Exact assurance scope and provider requirements should be confirmed against final regulations and standards. Reporting teams should nevertheless build for reproducibility now. An assurance practitioner will need to understand the reporting boundary, data flow, control owners, methods, estimates, changes, and evidence behind each disclosed metric.
Use the ISSA 5000 readiness framework to organize evidence even where Japanese assurance standards or local requirements add detail.
A readiness plan by reporting workstream
Reporting scope and governance
Confirm which listed parent reports, the entities included in its consolidated boundary, and the committees that oversee sustainability information. Align board and disclosure-committee calendars with the securities-report timetable.
Climate and GHG data
Create a complete Scope 1 and Scope 2 source register, then reconcile facilities and accounts to the consolidated group. Document methods, estimates, and emission-factor versions. For Scope 3, identify categories, owners, calculation methods, and a practical supplier-data improvement plan.
Strategy and financial connectivity
Connect identified sustainability risks and opportunities to business plans, risk registers, financial forecasts, and materiality decisions. Scenario analysis should preserve assumptions, model versions, review evidence, and an explanation of uncertainty.
Disclosure production
Run a dry report before the first mandatory year. Track every quantitative and narrative disclosure to an owner and supporting evidence. Review Japanese and group-level disclosures together so that translations and local adaptations do not create contradictions.
Work backward from assurance, not publication
A company reporting for the fiscal year ending March 2027 has little time to repair weak source systems after year-end. Quarterly collection and review make missing sites, unit errors, inconsistent boundaries, and unexplained variances visible while they can still be resolved.
The same principle applies to later cohorts. Their additional preparation time is most valuable when used to strengthen recurring controls, not to postpone the first complete inventory.
Information in this article was verified on August 9, 2026. Japanese implementing and assurance requirements may continue to develop. This overview is general information, not legal advice.
Sources
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