Thailand SEC Mandates ISSB Reporting for Listed Companies

Thailand's Securities and Exchange Commission has published regulations requiring all listed companies to file sustainability and climate disclosures aligned with the ISSB standards, with first reports due in 2028 covering fiscal 2027 and the full phase-in running through 2031.

The mandate replaces a flexible regime in place since 2022. Since then, listed companies have disclosed ESG performance, governance, human rights and greenhouse gas emissions in annual filings, but the SEC permitted them to use external frameworks such as the Global Reporting Initiative (GRI) Standards or TCFD recommendations rather than one standard.

The SEC launched a consultation in 2024 on moving sustainability reporting to the IFRS standards. The regulator's stated goals: improve international alignment and produce more consistent, comparable data across the market.

What is the phase-in schedule?

The regulation follows the size of the issuer and the exchange it trades on:

• 2028, on 2027 data: SET50 constituents, the 50 largest companies on the Stock Exchange of Thailand
• 2029: SET100 companies
• 2030: all other SET-listed companies
• 2031: all companies listed on the secondary mai exchange, plus REITs, infrastructure funds (IFFs and IFTs) and property funds (PFs)

How does the mandate treat emissions data?

The regulations require greenhouse gas emissions disclosures to be verified by assurance providers working to internationally accepted assurance standards. That verification requirement puts emissions data on a footing closer to financial audit than to voluntary ESG reporting.

The ISSB released its inaugural standards, IFRS S1 on general sustainability and IFRS S2 on climate, in June 2023. More than 45 jurisdictions have started the process of adopting the standards since then. Thailand now moves from consultation to a fixed calendar.

What transition relief do companies get?

The SEC built a series of reliefs into the rules to support companies building data systems and capabilities:

• Exemption from comparative information in the first year of reporting climate-related disclosures
• Flexibility in the reporting timeframe
• Permission to use equivalent GHG emissions calculation standards
• Exemption from Scope 3 emissions disclosure during the initial implementation period

The Scope 3 relief matters most for supply-chain-heavy issuers. Value-chain emissions are the hardest category to measure, and the temporary exemption gives smaller listed firms time to build supplier data pipelines before the requirement bites.

The first hard milestone arrives with SET50 filings in 2028 on 2027 data. Watch whether Thai regulators align assurance and Scope 3 timelines with peer jurisdictions adopting IFRS S1 and S2, and whether the 45-plus jurisdictions now moving on ISSB converge on a common first-reporting year.