30 September: The Cut-Off That Decides Thailand’s First FTSE4Good December Review

The FTSE4Good Thailand Index launched on 6 July 2026. In December it faces its first semi-annual review — and the date that decides the outcome is not in December at all. It is 30 September 2026.

Under FTSE Russell’s own rules, only company disclosures published by 30 September can be considered for the assessments that feed the December index review. Anything published on 1 October or later waits for the next cycle. As of today, that leaves 54 days.

For most SET-listed sustainability and investor-relations teams, the December review is still filed mentally under “Q4.” It is not. The work that determines it has to be finished, signed off and publicly online before the end of September. Here is precisely how the mechanism works — drawn from FTSE Russell’s published Ground Rules and FAQ, not from interpretation.

54 days to the only publication date that counts

FTSE Russell’s ESG Scores and Indices FAQ (v1.5, December 2025) is unambiguous at §1.6: “only company disclosures published by 30th September can be considered for assessments used in the December index review.” The research cycle itself runs from June to the following March, with the data analysis for December-review companies falling in October and November.

The index’s own Ground Rules (v1.0, June 2026) then set the measurement point: the FTSE4Good Thailand Index is reviewed semi-annually in June and December, with ESG screening applied to data as at the close of the last trading day in May and November respectively. So the December 2026 review freezes on end-November data — but the disclosure it reads must already have been published two months earlier.

This is the part that catches Thai issuers with December fiscal year-ends. Your 56-1 One Report for FY2025 went out in March. If your English sustainability disclosure has been refreshed, extended or corrected since — or if it has not yet been published at all — 30 September is the wall. Track the wider disclosure calendar →

The October window is a review — not a second chance

There is a widespread and expensive misreading of what happens next. Companies whose annual disclosures are published between April and September can expect an invitation to review their new assessment by the first weekend of October. Many teams treat that invitation as a chance to supply what they forgot to publish.

The Thai cycle has its own published calendar, and it is worth reading against today’s date. SET’s 2026 timeline for FTSE Russell ESG Scores runs: assessment by FTSE Russell June–August; the company review window, in which you see preliminary results and may submit additional information, September–October; FTSE incorporating that input and calculating scores October–November; scores delivered in December.

So your assessment is being conducted right now, and your review window opens in roughly four to six weeks — almost exactly as the 30 September publication cut-off passes. That ordering is the whole trap. By the time you see what FTSE could not find, the date for publishing it has gone.

It is not. FTSE Russell states plainly that “all the information we are looking for is based on materials already in the public domain.” The window is two to four weeks, and the FAQ is explicit: “We are therefore unable to accommodate extensions.” Companies may seek clarification on up to 10 indicators. Ten — across a model that applies roughly 125 indicators to a typical company.

So the only lever that moves your December score is what you publish before the cut-off. After that, you are auditing FTSE’s reading of a document you can no longer change.

2.9 to get in, 2.3 to fall out

The Ground Rules set two different bars, and boards routinely conflate them. To be added to the FTSE4Good Thailand Index — derived from the FTSE SET All-Share Index — a company needs an ESG Score of 2.9 or above. A company already in the index only falls into deletion risk at 2.3 or lower, and then gets a grace period: it is deleted at the index review one year later if the criteria are still not met.

Between 2.4 and 2.9 sits a band where an existing constituent remains eligible but a new applicant is not. If you are outside the index and scoring 2.6, you are not “nearly in” — you are out, and you stay out until you publish enough to clear 2.9. The same thresholds appear in the wider FTSE4Good Index Series Ground Rules (v6.0, May 2026) as the emerging-market bars; the developed-market equivalents are 3.3 and 2.9, and quoting those at a Thai company is a common and costly error.

The published data shows how much those secondary gates matter. FTSE Russell assessed 222 Thai companies in 2025, and the distribution is genuinely strong — roughly 84% scored above 3.0, comfortably clear of the 2.9 bar. Yet only 119 of the 250 FTSE SET All-Share constituents made the index at launch. For most of that gap the headline score was never the binding constraint: the exclusions, the High Exposure Theme rule and the climate gate were. And Thailand’s weakest of the fourteen themes is Climate Change, at 2.75 — below the 3.0 that primary-impact subsectors must clear, and well below the FTSE Developed average of 3.25.

The hard block deserves its own line. A Theme Score of zero in a single applicable High Exposure Theme stops inclusion regardless of how strong the rest of your profile is. FTSE’s model runs three pillars, 14 themes and 300+ indicators, with exposure weighted Low, Medium or High by sector. A theme you are genuinely strong on — but which a reader cannot find in English — scores as absent. Compare how each rater reads you →

Thai satisfies the SEC. English earns the score.

Which brings us to the mechanism underneath all of it. FTSE Russell does not send a questionnaire. It scores — on its own FAQ’s count — over 8,500 companies from public disclosure. And that same FAQ, at §1.8, lists the languages provided for in the research process: English, French, Spanish, German, Japanese and Chinese.

Thai is not on that list.

A Thai-language One Report discharges your obligation to the Thai SEC completely. It does not earn a single FTSE point. The English edition is the artefact that gets scored — which makes it a piece of investor-relations infrastructure, not a translation line item. This is the whole case for the English edition →

The failure mode we see most often is not an absent English report. It is an English report that is thinner than its Thai parent: a governance theme summarised into two sentences, a human-rights policy referenced but not restated, a climate target expressed in Thai units and quietly dropped. Each of those reads to an analyst as a gap, and gaps score as zero. See where disclosure language turns into rating risk →

What to do with the 54 days

Fifty-four days is short but it is not nothing. It is enough to publish, and publishing is the only thing that counts. A realistic sequence:

Two things make this tractable inside eight weeks. First, most of the substance already exists — it is in Thai, in your One Report, in your TGO certificates. The work is making it legible in English, not inventing it. Second, the carbon numbers behind the environmental themes are usually the long pole, and if they are already TGO-certified you can move straight to disclosure →.

Running underneath this is Thailand’s own ISSB transition — and if you are working to a FY2026 date for SET50, that date has moved. Following consultation, the SEC revised its ISSB roadmap in November 2025 and deferred the first two groups by a year each: SET50 now commences in 2027 and SET100 in 2028, with the wider SET in 2029 and mai and REITs in 2030. Stale FY2026 timelines are still circulating widely, in part because the SEC publishes its phase-in table as an image rather than as text.

That is breathing room on the filing, not on the work — and it makes the FTSE deadline the nearer one by some distance. The English disclosure you publish this September is the same disclosure that has to withstand IFRS S1 and S2 when it does land, which is an argument for building it properly once. Start with TSRS S1 & S2 readiness →, and clause-map both editions so they finally agree →.

Two things raise the stakes on this particular cycle. 2026 is the first year the scores go public. SET will announce them on its own channels for every assessed company — including those scoring 0.0. Under the retired SET ESG Ratings only companies clearing the bar were ever named, so a weak result stayed invisible. It will not be this December. And SET’s own guidance is that fund managers begin using FTSE4Good Thailand as a benchmark from January 2027. A thin score is about to become both visible and investable.

The December 2026 review is Thailand’s first real test under a methodology that does not ask questions. The companies that clear it will be the ones that treated 30 September as the deadline it actually is.

Sources: FTSE Russell, ESG Scores and Indices FAQ v1.5 (December 2025), §§1.6, 1.8, 1.9, 1.16, 1.21; FTSE Russell, FTSE4Good Thailand Index Ground Rules v1.0 (June 2026), §§6.1, 7; FTSE Russell, ESG Data Model Methodology v1.2 (June 2026), §§1.4, 1.6; FTSE Russell, FTSE4Good Index Series Ground Rules v6.0 (May 2026); SET × FTSE Russell, The Guideline to FTSE Russell ESG Scores and the published 2026 assessment timeline (setsustainability.com); FTSE Russell (Irene Jee), Where Thai companies stand in the global ESG landscape, 16 February 2026; FTSE4Good Thailand Index factsheet, data as at 31 July 2026; LSEG press release, FTSE4Good Thailand Index launch (6 July 2026); ADB Brief No. 387, Adopting Global Sustainability Disclosure Standards in Thailand (April 2026), Table 3, for the revised SEC ISSB phase-in.