Thailand has taken a significant step toward standardized corporate sustainability reporting, introducing mandatory disclosures aligned with the International Sustainability Standards Board (ISSB).

On October 28, 2026, Thailand’s Securities and Exchange Commission (SEC) announced finalized regulations requiring listed companies and certain investment entities to progressively adopt reporting requirements based on IFRS S1 and IFRS S2, the international sustainability disclosure standards developed by the IFRS Foundation.

The new rules will apply in phases, beginning with the country's largest publicly traded companies for their 2027 reporting year, with initial reports due in 2028.

For companies operating in Thailand's capital markets, the development signals a shift toward more consistent, investor-focused sustainability disclosures, supported by mandatory external verification of greenhouse gas (GHG) emissions information.

A New Standard for Corporate Sustainability Disclosure

Thailand has required listed companies to disclose environmental, social, and governance (ESG) information through annual reporting since 2022. However, the existing framework allowed companies to reference different sustainability reporting standards.

The updated regulations introduce a more standardized approach aligned with two internationally recognized frameworks:

• IFRS S1 — General Requirements for Disclosure of Sustainability-related Financial Information: Establishes requirements for disclosing material sustainability-related risks and opportunities that could affect a company's financial prospects.

• IFRS S2 — Climate-related Disclosures: Establishes requirements for reporting climate-related risks, opportunities, governance, strategy, risk management, and performance metrics.

Together, these standards provide investors with a more consistent basis for assessing how companies identify and manage sustainability-related financial risks.

Thailand's implementation will initially emphasize climate-related information, supported by transitional measures designed to help businesses adapt.

Implementation Will Begin With Thailand's Largest Companies

Rather than requiring every company to comply immediately, the SEC has established a phased implementation schedule.

The phased approach allows smaller listed companies additional time to develop internal reporting capabilities and prepare for the new disclosure requirements.

Importantly, companies should assess applicability based on their securities listings and regulatory classification, rather than simply their operating presence in Thailand. Foreign-incorporated companies with relevant Thai listings may also fall within scope, while privately held companies are not automatically subject to the mandate.

Carbon Emissions Reporting Will Require Independent Verification

One of the most consequential features of the new regulations is the requirement for external verification of reported greenhouse gas emissions.

During the initial implementation phase, the framework emphasizes:

• Scope 1 emissions: Direct emissions from sources owned or controlled by the company.

• Scope 2 emissions: Indirect emissions associated with purchased electricity, steam, heating, or cooling.

• Independent verification: Reported GHG emissions information must be verified by assurance providers using internationally accepted assurance standards.

These requirements will place greater emphasis on emissions data quality, internal controls, and the ability to substantiate reported figures.

For companies that currently rely on estimates or decentralized emissions calculations, preparing reliable, verifiable information may require additional coordination across operational and financial reporting teams.

Transitional Flexibility Gives Companies Time to Adapt

Recognizing the operational challenges associated with implementing international sustainability standards, the SEC has introduced five transitional relief measures.

These include flexibility around reporting timeframes, an exemption from comparative climate-related information in the first reporting year, permission to use equivalent GHG calculation standards, and temporary relief from Scope 3 emissions disclosures during the initial implementation period.

Scope 3 emissions represent indirect emissions across a company's value chain, including certain supplier, transportation, and product-use activities. The relief measures should help companies establish their reporting systems before transitioning toward more comprehensive disclosures.

However, organizations should not interpret these accommodations as a reason to defer preparations. Collecting emissions data, establishing governance processes, and arranging independent verification can require significant coordination across business functions.

What This Means for Multinational Businesses

Thailand's adoption of ISSB-aligned standards reflects the increasing international convergence of sustainability reporting requirements. Companies already preparing disclosures under IFRS S1, IFRS S2, or similar climate reporting frameworks may be able to leverage existing processes and data.

Nevertheless, multinational organizations should consider several practical implications. First, companies with Thai-listed subsidiaries or other covered entities should assess whether those entities fall within the SEC's phased reporting requirements. Operating in Thailand alone does not establish direct applicability.

Second, organizations should evaluate the consistency of climate-related information across their global operations, particularly where reporting requirements differ between jurisdictions.

Finally, businesses should determine whether their existing emissions reporting processes are sufficiently documented and controlled to support independent verification.

Even where a multinational parent company is already preparing sustainability disclosures elsewhere, local reporting obligations may require additional entity-level information, adjustments to reporting formats, or jurisdiction-specific compliance processes.

Preparing for Thailand's New Reporting Framework

With the first reporting period beginning in 2027, affected organizations should prioritize three areas of preparation:

1. Confirm applicability and reporting dates. Identify covered Thai-listed entities, determine their applicable reporting phase, and review the SEC's updated Form 56-1 One Report-S requirements.

2. Assess reporting readiness. Compare existing sustainability disclosures with the applicable IFRS S1 and IFRS S2 requirements, taking Thailand's transition relief measures into account.

3. Strengthen data collection and assurance readiness. Establish reliable emissions inventories, supporting documentation, internal responsibilities, and verification processes.

For larger listed companies, the immediate priority is ensuring that the systems required to capture 2027 information are ready before the reporting year begins.

Looking Ahead: A More Consistent Reporting Landscape in Asia

Thailand's finalized regulations mark another step toward the broader adoption of international sustainability reporting standards across Asia. Although implementation will occur gradually through 2031, the first affected companies will need to begin collecting information under the new framework in 2027.

The direction is clear: sustainability reporting is becoming increasingly standardized, financially relevant, and subject to independent scrutiny.

For businesses with exposure to Thailand's capital markets, early preparation will be essential to meeting the new requirements efficiently while maintaining consistency with broader global sustainability reporting obligations.