ส่งมอบ 28 October 2026, Thailand’s Securities and Exchange Commission published news release 231/2569, under the headline that it is raising listed companies’ sustainability disclosure rules to the ISSB standards, starting in 2027. The release says the SEC has issued nine notifications, in force from 26 October 2026, together with a new Form 56-1 One Report-S and a manual for preparing it.
For two years, Thai sustainability teams have planned against consultation papers and draft forms. That stage is over. The rules that will govern the first IFRS S1 and S2 reports in Thailand now exist, and the first group of companies will be fixed in about six weeks, when SET runs its December 2026 SET50 review.
What the SEC announced on 28 October
The release itself is short. It says the SEC has issued the notifications needed to bring listed-company disclosure in line with IFRS S1 and IFRS S2, published the revised annual-filing form (Form 56-1 One Report-S) and a preparation manual on its website, and will continue training with domestic and foreign partners. The detail sits in the SEC’s own training deck on the new form, dated 21 October 2026, which sets out the phase-in, the reliefs and the assurance expectations.
The form has its own structure. Sustainability-related financial information goes into Part 1 under risk (sections 2.1 and 2.2) and a new section 3 on driving the business for sustainability: 3.1 on the requirements for sustainability-related financial disclosure, 3.2 on strategy and plans, 3.3 on metrics, targets and performance, and 3.4 on material events after the reporting date. Part 2 adds section 7.4, on the board, committees or persons responsible for sustainability. That last item puts a name, not just a policy, in the filing.
Who reports, and when
The phase-in matches the revised principles the SEC announced in November 2025 (News 298/2568), which moved SET50 and SET100 back by one year each. Membership is fixed by a specific index review, not by whatever the index looks like when you file:
LiVEx companies and unlisted companies are outside the scope. Companies not yet in scope may disclose voluntarily. One practical point: the December 2026 SET50 list has not been published yet. On past practice, SET announces its December review in mid-December, with effect from January. If your company sits near the SET50 boundary, you will learn whether FY2027 is your first ISSB year only a few weeks before it starts. We covered that boundary problem in our note on the December 2026 review.
The five reliefs, and the one thing with no relief
The release lists five transition reliefs. SET’s ISSB roadmap hub gives their durations, counted from the year the rules first apply to each group:
Full IFRS S2 plus the relevant parts of S1. Other sustainability topics can be handled on a comply-or-explain basis.
Scope 3 emissions can be disclosed after the relief period ends. For SET50, that means a first mandatory Scope 3 figure well into the 2030s.
One Report-S may be filed at a different time from the annual financial statements. The SEC deck says within three months of the financial year-end.
Companies may use an equivalent, nationally accepted method, such as TGO’s, instead of the GHG Protocol at first. The SEC deck says TGO’s method is not different from the GHG Protocol for Scope 1 and 2.
Assurance is ไม่ได้ on that list. The release says greenhouse gas data must be verified by an assurance provider working to recognised international standards. The SEC deck says the expectation is external limited assurance, or higher, to ISAE 3410 or TSAE 3410, ISSA 5000 or TSSA 5000, ISO 14064-3 or AA1000, by a TGO-registered verifier or another qualified verifier. For the SET50 cohort that means assured Scope 1 and 2 numbers for FY2027 from the first filing. Our guide to TSSA 5000 and what the assurance scope covers explains the choice of standard, and TGO CFO certification is where most Thai inventories start.
The deck also sets an expectation on scenarios. IFRS S2 uses climate scenario analysis to assess resilience rather than to identify risks, and the SEC says companies can choose at least two scenarios, qualitative or quantitative.
What we said before, and what has changed
In September we wrote that none of this had been gazetted and that the One Report-S form was still a draft. That was accurate then. It is no longer accurate. This is what changed on 26 to 28 October:
| Before 26 Oct 2026 | From 26 Oct 2026 | |
|---|---|---|
| Legal status | Principles (News 298/2568) and draft notifications | Nine notifications in force |
| Form 56-1 One Report-S | Consultation draft (Sept 2025) | Final form + preparation manual |
| SET50 first data year | FY2027 (revised principles) | FY2027, Dec 2026 review |
| GHG assurance | Proposed | Required, no transition relief |
| IFRS Foundation profile | Shows SET50 on FY2026 | Still not updated, so do not rely on it for dates |
That last row matters if your team works from global trackers. The IFRS Foundation’s Thailand jurisdictional snapshot was last updated in June 2025 and still shows the earlier timetable. The SEC’s release and SET’s roadmap hub are the sources to use. We keep the live dates on our ESG regulatory tracker.
The language question the rules do not answer
Neither the release nor the SEC’s training deck says anything about the language of One Report-S. The standards are referred to by their English names, IFRS S1 and IFRS S2, and no official Thai translation of either has been published yet. The Federation of Accounting Professions lists translating them into Thai among its roles.
The existing annual-filing rule, clause 37 of SEC Notification TorJor. 44/2556, says reports to the SEC are made in Thai. Clause 38 lets a company also file an English version, provided the substance of the information does not differ from the Thai and the English version carries a certification of its accuracy. The SEC’s One Report FAQ is plain that this clause was not intended to compel an English translation. We have not seen the final notification text, so we cannot say how that rule applies to One Report-S. If anything changes, it will be in those notifications, not in the press coverage.
So the English edition is still a choice. It is a choice with consequences. FTSE Russell scores Thai companies from public disclosure, without a questionnaire, and Thai is not among the key research languages its FAQ names:
Although English is the commonly used business language, FTSE Russell recognizes the importance of local languages. … The key languages covered are as follows: English, French, Spanish, German, Japanese and Chinese.
FTSE Russell ESG Scores and Indices FAQ, v1.5 (December 2025), §1.8For an exporter, CBAM is where the choice disappears: Commission Implementing Regulation (EU) 2025/2547 requires the operator’s emissions report to be submitted in English (Art. 10(4)), and see our CBAM guide for Thai exporters. For the One Report-S itself, the point is control. A global analyst will read the English edition. If you publish one, clause 38 already puts an equivalence duty on it. So the English edition of a first ISSB report should be checked against the Thai, figure by figure and term by term, before it goes out. That is what a clause-mapped bilingual One Report does. Our FTSE English-disclosure note explains the readership argument in more detail.
Where the evidence runs out
Three limits, stated plainly. First, we read the release through its official wire copies and the SEC’s news list; we have not yet read the nine notifications themselves, and we do not quote their numbers here. Second, the three-month filing window comes from the SEC’s training deck, not the release. Third, there is no evidence that Thai-language disclosure is scored down. SET’s own data shows Thai companies’ FTSE ESG Scores rising across every industry group in the 2025 round, and FTSE publishes Thai-language indicator material. The case for the English edition is readership and accuracy, not a penalty.
It is also worth some perspective on the region. Malaysia’s largest listed companies have applied IFRS S1 and S2 since 2025, and on 17 September 2026 Malaysia’s Securities Commission deferred mandatory reasonable assurance of Scope 1 and 2 to periods starting on or after 1 January 2028. Singapore’s Straits Times Index constituents report Scope 3 from FY2026. Thailand starts later and with longer reliefs. It is not ahead of its neighbours; it now has a fixed timetable.
What to do before the December SET50 review
The FY2027 inventory for a SET50 company starts on 1 January 2027. Most of what follows has to be in place before then:
- Check where you sit against the SET50 cut-off now, before SET publishes the December 2026 review.
- Map your current 56-1 sustainability content to One Report-S sections 2.1–2.2, 3.1–3.4 and 7.4, and name the person responsible under 7.4.
- Fix your GHG method (TGO CFO or GHG Protocol) and book a verifier for limited assurance of FY2027 Scope 1 and 2. There is no relief on assurance.
- Choose at least two climate scenarios and decide whether the analysis is qualitative or quantitative.
- Decide on the English edition early. If you publish one, build it to the clause 38 standard: same substance as the Thai, certified accurate.
Is your first One Report-S on track?
We map your current disclosure to the new form, build the TGO-certified carbon numbers behind it, and produce an ISO 17100 English edition that matches the Thai clause by clause.
See TSRS S1 & S2 readinessThe first Thai ISSB reports will be filed in 2028, on data that starts accumulating in nine weeks. For the full SET50 timeline see SET50’s first climate disclosure, and for how TGO carbon data feeds into rated disclosure see TGO carbon to FTSE disclosure. Our ISO 17100 technical translation service covers the English edition.
Sources: SEC Thailand, News 231/2569 (28 Oct 2026), as listed on sec.or.th and carried in full by ThaiPR and InfoQuest (28 Oct 2026); SEC Thailand, training deck “Preparing and disclosing information under Form 56-1 One Report-S” (21 Oct 2026); SEC Thailand, News 298/2568 (28 Nov 2025); SET, ISSB Information Hub: Thailand adoption roadmap (setsustainability.com); SEC Notification TorJor. 44/2556, clauses 37–38, and SEC One Report FAQ; IFRS Foundation, Thailand jurisdictional snapshot (updated 12 Jun 2025); FTSE Russell ESG Scores and Indices FAQ v1.5 (Dec 2025), §1.8 and §2.9; Commission Implementing Regulation (EU) 2025/2547, Art. 10(4); Securities Commission Malaysia media release (17 Sep 2026); ACRA, sustainability reporting requirements timeline. Translations from Thai sources are ours.
Related: Othello is a contracted ISSB Training Partner — see our ISSB Disclosure Training in Thailand on IFRS S1 and IFRS S2.
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