IFRS S1 & S2 in Thailand: Disclosure Guide for SET-Listed Firms

IFRS S1 and IFRS S2 — the first two standards from the International Sustainability Standards Board (ISSB) — are quickly becoming the global baseline for sustainability and climate disclosure. For Thai listed companies, they are not a distant concern: they are being phased into the SET reporting framework, and they sit directly behind the FTSE Russell ESG Scores that replace the SET ESG Ratings from 2026. This guide explains what IFRS S1 and S2 require, the Thai adoption timeline, and how to prepare disclosure that is both compliant and investor-ready.

What are IFRS S1 and IFRS S2?

Both standards are built on the same four-pillar structure made familiar by the TCFD — governance, strategy, risk management, and metrics and targets — but applied with the rigour of financial reporting.

• IFRS S1 — General Requirements for Disclosure of Sustainability-related Financial Information. It requires a company to disclose the sustainability-related risks and opportunities that could reasonably affect its cash flows, access to finance, or cost of capital over the short, medium and long term.
• IFRS S2 — Climate-related Disclosures. It is climate-specific and works alongside S1, requiring disclosure of climate risks and opportunities, transition plans, and — critically — Scope 1, 2 and 3 greenhouse gas emissions measured in line with the GHG Protocol.

The defining principle of both is that sustainability information is treated as decision-useful financial information — connected to the financial statements, assured to a higher standard, and reported on the same timeline.

The IFRS S1/S2 timeline for Thailand

Thailand has signalled clear support for the ISSB baseline, and the Stock Exchange of Thailand and the SEC are aligning the local framework accordingly. Under the expected phase-in, the largest listed companies move first: SET50 companies from 2027, followed by SET100 companies from 2028, with broader application over time. Because timelines and transitional reliefs are still being finalised, companies should confirm the current requirements with the SEC and their auditors — but the direction of travel is settled, and the largest issuers are already in scope.

What you will need to disclose

• Governance — the board and management processes used to oversee sustainability and climate risks and opportunities.
• Strategy — the effects of those risks and opportunities on the business model, strategy and financial planning, including climate scenario analysis and any transition plan.
• Risk management — how sustainability and climate risks are identified, assessed and integrated into overall risk management. A robust double materiality assessment underpins this.
• Metrics and targets — including Scope 1, 2 and 3 GHG emissions, internal carbon prices, and the targets used to manage performance.

The difference between IFRS S1 and IFRS S2

A common source of confusion is how the two standards relate. Think of IFRS S1 as the overarching rulebook and IFRS S2 as the first topic-specific chapter written under it. IFRS S1 sets the general requirements: it tells you how to identify and report any sustainability-related risk or opportunity that could affect enterprise value — the concepts of materiality, the connectivity to the financial statements, the reporting timing, and the four-pillar structure. IFRS S2 then applies that machinery to a single subject, climate, with detailed, prescriptive requirements including mandatory greenhouse-gas emissions disclosure.

For a Thai issuer, the practical implication is that you cannot treat S2 as a standalone climate report bolted onto the annual report. It has to inherit S1’s discipline — the same materiality judgements, the same connection to the numbers in the financial statements, and the same reporting calendar. Climate content that contradicts the financial statements, or that rests on a different materiality basis from the rest of the sustainability disclosure, is exactly what assurance is designed to catch.

Common pitfalls in first-time IFRS S1/S2 reporting

Companies preparing their first ISSB-aligned disclosure tend to stumble in the same predictable places. Knowing them in advance turns a scramble into a managed project.

• Underestimating Scope 3. Value-chain emissions are the hardest to measure and the easiest to defer — but they are required, and building the inventory late is the single most common cause of a disclosure that cannot be assured.
• Boilerplate governance language. Copying generic board-oversight statements from a template fails the standard’s intent, which is to describe the actual processes your board uses to oversee climate risk.
• Disconnected data. Sustainability figures compiled in a spreadsheet that never reconciles with the financial statements or the reporting calendar create contradictions a reviewer will find.
• Thai–English drift. A target or boundary described one way in Thai and differently in English produces two conflicting “official” versions of the same disclosure — a needless risk explored below.

The bilingual dimension: why the English version is material

For SET-listed companies, IFRS S1/S2 disclosure is prepared in Thai but read, scored and relied upon in English. FTSE Russell, MSCI and global investors work from the English-language version of your 56-1 One Report and sustainability report. That makes the English text not a courtesy translation but part of the disclosure itself — and any divergence between the Thai and English versions is a genuine reporting risk.

The exposure is rarely a crude mistranslation. It is precision and register: an aspiration in Thai hardening into a firm commitment in English, an emissions boundary or base year described inconsistently, a defined target softening into vague intention and losing scored indicators. Because IFRS S1/S2 information is assured to a financial-reporting standard, these are not cosmetic issues — they are potential misstatements. Reconciling both languages against one agreed meaning, rather than translating sequentially, is what keeps the two versions identical. This is precisely where ISO 17100-certified, disclosure-grade bilingual work earns its place in the reporting process.

How IFRS S1/S2 connects to the 56-1 One Report and your FTSE score

These standards do not sit in isolation. The disclosures land in the sustainability section of your 56-1 One Report, and that public, English-language disclosure is precisely what FTSE Russell reads to calculate your score. In other words, IFRS S1/S2, the 56-1 One Report, and the move from SET ESG Ratings to FTSE Russell ESG Scores are three views of the same underlying requirement: high-quality, public, bilingual disclosure.

How to prepare

• Run a gap assessment against the IFRS S1/S2 disclosure requirements to find where your current reporting falls short.
• Complete or refresh a double materiality assessment to define which sustainability topics are reportable.
• Build a defensible Scope 1, 2 and 3 GHG inventory aligned with the GHG Protocol.
• Connect sustainability data to the financial statements and the reporting calendar, not a separate year-end scramble.
• Produce the disclosure in high-quality English as well as Thai — it is read by global investors, auditors and the rating model itself.

Frequently asked questions

Is IFRS S2 the same as TCFD? IFRS S2 builds on and consolidates the TCFD recommendations, with more prescriptive requirements — including mandatory Scope 1, 2 and 3 emissions disclosure. Companies already reporting under TCFD have a strong head start.

Do we have to report Scope 3 emissions? Yes, IFRS S2 requires Scope 3 disclosure, though transitional reliefs may apply in the first reporting periods. Building the inventory early is the safest course.

Does the disclosure need to be in English? For SET-listed companies, bilingual disclosure is the norm — and because IFRS S1/S2 information feeds your FTSE Russell score and reaches global investors, the quality of the English version is material.

When do IFRS S1/S2 requirements start in Thailand? Under the expected phase-in, the largest issuers move first — SET50 from 2027 and SET100 from 2028 — with broader application over time. Confirm your specific timing with the SEC and your auditors, as transitional reliefs are still being finalised.

Prepare for IFRS S1/S2 with the right partner

Othello International combines ESG advisory — double materiality, GHG inventory and disclosure-gap assessment — with disclosure-grade bilingual translation built for SET-listed companies. We help you produce IFRS S1/S2-aligned reporting that is compliant, FTSE-ready and clear in both languages. Talk to our team to benchmark your readiness.

Related ESG guides

• SET ESG Ratings Explained (2026): Criteria, Results, and the Shift to FTSE Russell
• Scope 1, 2 & 3 GHG Inventory for Thai Companies (TGO-Aligned)
• Double Materiality Assessment, Explained for Thai Issuers
• SET Moves to FTSE Russell ESG Scores in 2026: What SET-Listed Boards Must Do
• GRI vs SASB vs IFRS S1/S2: ESG Reporting Frameworks Explained (2026)

Related Othello services

• IFRS S1/S2
• TCFD Implementation
• Climate & IFRS S2 Disclosure

📘 Free resource: Explore The FTSE 2026 Playbook Library — Othello’s ESG disclosure playbook plus focused editions for Thai banks, energy, property, healthcare, technology and more.

Related services from Othello International

Othello International is a Bangkok-based bilingual (EN↔TH) technical translation and ESG advisory firm. Related specialist services:

• climate & IFRS S2 disclosure — TCFD four-pillar
• ESG disclosure translation — IFRS S2, GRI, FTSE-ready
• GHG inventory — Scope 1/2/3, TGO-aligned
• ESG ratings submissions — FTSE, MSCI, S&P, SET