Last updated: May 25, 2026. Thailand sustainability reporting is already mandatory for listed companies through Form 56-1 One Report. The current requirement sits inside the annual registration statement and annual report, and asks listed companies to disclose how the business manages sustainability, stakeholders, environmental impacts, social impacts, greenhouse gas emissions, and related governance topics.
Short answer: Thailand does not have a single sustainability report law for every private company. The core mandatory regime applies to listed companies through Form 56-1 One Report, which must generally be filed within three months after the fiscal year end. Thailand's SEC is also moving listed-company disclosure toward ISSB-aligned reporting under IFRS S1 and IFRS S2. The latest SEC position keeps ISSB alignment as the direction of travel, but the SEC revised the principles in November 2025 and is still amending the relevant regulations and documents. Companies should treat Form 56-1 One Report as the current operative requirement and prepare for ISSB-style climate and GHG disclosure as the next layer.
Who needs to report sustainability information in Thailand?
The current mandatory sustainability disclosure route applies mainly to companies listed on the Stock Exchange of Thailand through the annual Form 56-1 One Report process. The SEC introduced the One Report model to consolidate the annual registration statement and annual report, and it became effective for financial periods ending December 31, 2021, with filing from January 1, 2022 onward.
In practice, the first question is whether the entity is:
- a listed company on SET or mai;
- a company preparing for an IPO or public securities offering;
- a REIT, infrastructure trust, property fund, or infrastructure fund subject to SEC reporting documents;
- a Thai or foreign company with primary, secondary, or dual listing exposure; or
- a private company receiving sustainability, GHG, ESG-rating, or buyer reporting requests from investors, banks, enterprise customers, or parent-company reporting teams.
Private companies outside those channels may still need sustainability data for finance, procurement, supply-chain, or voluntary reporting reasons, but Form 56-1 One Report is primarily a listed-company disclosure regime.
What Form 56-1 One Report requires today
The sustainability content sits mainly in the business sustainability development section of Form 56-1 One Report. The SEC describes the One Report as improving disclosure by showing how the business operates under environmental, social, and governance principles, including policies, goals, ESG performance, greenhouse gas emissions, and respect for human rights.
The main sustainability disclosure areas are:
- Policy and objectives of sustainable management: sustainability policies, objectives, business integration, and changes in policy or targets.
- Stakeholders and value chain: the company's value chain, stakeholder groups, stakeholder expectations, business impacts, and responses.
- Environmental sustainability management: environmental policies, legal alignment, climate or environmental targets, action plans, operating results, greenhouse gas emissions, waste, energy, water, and environmental compliance where relevant.
- Social sustainability management: labor practices, human rights, occupational health and safety, employee development, community engagement, responsible production, and social-performance results.
- Compliance and incidents: explanations of significant environmental or social non-compliance, violations, remediation, and preventive measures where applicable.
When is Form 56-1 One Report due?
The normal filing deadline for Form 56-1 One Report is within three months after the fiscal year end. SET notes that submission through SETLink is treated as submission to the SEC for listed companies. This makes sustainability reporting part of the broader annual reporting timetable, not a separate communications project that can be prepared after the financial report is finished.
Companies should therefore collect ESG and GHG data during the year, assign data owners early, and align sustainability drafting with finance, risk, legal, investor relations, HR, operations, EHS, and corporate secretary teams.
GHG reporting in Thailand
Greenhouse gas emissions disclosure is already part of the One Report context. For many listed companies, the practical question is no longer whether to mention climate and emissions, but whether the data is complete, calculated consistently, and ready for investor scrutiny.
The next ISSB-aligned layer is more technical. In the SEC's 2025 draft and revised principles, listed companies would disclose Scope 1 and Scope 2 GHG emissions and identify an assurance provider. The SEC also describes transition reliefs, including a period when Scope 3 emissions can be omitted and companies can disclose only Scope 1 and Scope 2 GHG emissions. Because final amended documents are still being completed, companies should use this period to build capability rather than wait for final filing templates.
ISSB alignment: what is changing?
Thailand's SEC has been moving toward sustainability-related financial disclosure aligned with the ISSB Standards. In 2024 and 2025, the SEC consulted on principles and draft regulatory amendments to align Thai listed-company disclosure with IFRS S1 and IFRS S2.
The September 2025 draft amendments proposed changes to Form 56-1 One Report-S and related documents, including scope, effective timeline, GHG emissions disclosure, limited assurance, and transition reliefs. In November 2025, the SEC announced revised principles. It maintained the direction of applying IFRS S1 and IFRS S2, with an initial climate-first approach focused on Scope 1 and Scope 2 GHG emissions and standardized assurance. It also revised the scope and timeline principles, including classification by SET index groupings such as SET50 and SET100.
As of this update, the most careful interpretation is: Form 56-1 One Report remains the current operative requirement, while ISSB-aligned disclosure is the reform path companies should prepare for. Companies should monitor the SEC's final amended regulations and disclosure documents before locking filing assumptions.
Thailand Taxonomy Phase 2
Thailand's sustainability reporting context is also shaped by the Thailand Taxonomy. Phase 1 covered energy and transport. Thailand Taxonomy Phase 2, published on May 27, 2025, expanded coverage to agriculture, construction and real estate, manufacturing, and waste management. These are high greenhouse gas-emitting sectors and are important for green finance, transition finance, and consistent environmental classification.
The taxonomy is not the same thing as Form 56-1 One Report. It does not replace the listed-company annual disclosure requirement. But it can affect how companies, lenders, investors, and issuers classify environmentally sustainable activities, assess transition plans, and communicate climate-related opportunities and risks.
What companies should prepare
For Thailand sustainability reporting, companies should start with a reporting map rather than a generic ESG narrative. A practical checklist includes:
- confirming which SEC or SET reporting document applies to the entity;
- mapping current Form 56-1 One Report sustainability requirements to existing report sections;
- assigning owners for policy, stakeholder, environmental, social, governance, risk, and GHG data;
- collecting energy, fuel, electricity, water, waste, employee, human rights, safety, community, and compliance evidence;
- calculating Scope 1 and Scope 2 emissions, and screening Scope 3 readiness;
- documenting methodologies, boundaries, emission factors, assumptions, and exclusions;
- checking whether environmental or climate activities should be mapped to the Thailand Taxonomy;
- preparing for GHG assurance readiness, even before final ISSB-aligned filing templates are settled; and
- monitoring final SEC regulations, One Report-S documents, and ISSB transition relief details.
Common reporting mistakes
The first mistake is treating Form 56-1 One Report sustainability disclosure as a narrative-only exercise. Investors and regulators increasingly expect specific evidence behind targets, emissions, policies, stakeholder management, and social or environmental performance.
The second mistake is assuming that a standalone GRI-style sustainability report automatically satisfies Thai annual disclosure requirements. Voluntary frameworks can help, but the company should map them back to Form 56-1 One Report and, for future readiness, IFRS S1 and IFRS S2.
The third mistake is waiting for final ISSB-aligned regulations before building GHG capability. Even if final templates change, Scope 1, Scope 2, governance, risk management, metrics, targets, and assurance-readiness work will remain useful.
How Keslio can help
Keslio helps companies turn Thailand sustainability reporting requirements into a practical reporting workplan, data request, and finished disclosure. Depending on the trigger, we can support:
- Form 56-1 One Report sustainability section gap checks;
- ISSB / IFRS S1 and IFRS S2 readiness reviews;
- GHG emissions calculations for Scope 1, Scope 2, and relevant Scope 3 categories;
- GHG data methodology notes and evidence trackers;
- Thailand Taxonomy mapping support where relevant to the business or financing need;
- sustainability reporting and communications for annual report or standalone reporting work; and
- supplier request support where the reporting trigger comes from a customer or buyer rather than the SEC.
This guide is not legal advice. If your company is preparing a formal filing, interpreting final SEC regulations, or determining legal reporting obligations, legal counsel should confirm the obligation while Keslio supports the sustainability data and reporting workstream.
Sources and further reading
- Thai SEC One Report resource page
- Thai SEC announcement preparing listed companies for Form 56-1 One Report
- Thai SEC reporting deadline guidance under Section 56
- SET periodic disclosure guidance
- Thai SEC September 2025 ISSB public hearing announcement
- Thai SEC November 2025 revised ISSB principles announcement
- Bank of Thailand joint press release on Thailand Taxonomy Phase 2
