The State of Thai Corporate Climate Disclosure 2026 — Full Report | Othello

One rating retires. The scored surface moves.

2025 was the last year of the SET ESG Rating as Thailand’s domestic benchmark. A record 265 listed companies qualified — roughly 70% of combined SET and mai market capitalisation — and then the regime itself was retired. From 2026, the Stock Exchange of Thailand publishes FTSE Russell ESG Scores in its place, alongside the newly launched FTSE4Good Thailand Index built with LSEG.

Two transition details matter for planning. First, the legacy SET ratings still govern ThaiESG-fund eligibility until December 2026 — the old scores keep financial consequences for one more window even as the new methodology takes over. Second, the FTSE pilot ran through 2024–2025 with scores undisclosed, which means the first scores most issuers ever see under the new regime arrive with the 2026 cycle, calculated from disclosure many of them wrote for the old one.

How the new score actually works.

The FTSE Russell ESG Score runs 0–5, built from three pillars (Environmental, Social, Governance) and 14 themes. Each theme’s weight is set by the company’s exposure — High (3), Medium (2), Low (1), or Not Applicable (0) — determined largely by sector. Exposure does two things at once: it sets how much a theme counts, and it raises the bar a high-exposure company must clear to score well on it.

The climate exception

Climate Change is the one theme that does not follow the standard percentage-of-indicators method. It is scored on TPI Management Quality — a staircase from Level 0 to Level 5 across 23 indicators — combined with carbon-emissions performance relative to peers. The staircase climbs in recognisable steps: a policy exists → targets are set → Scope 1 & 2 are quantified → board oversight, Scope 3 and verification appear → scenario analysis, executive-pay linkage and internal carbon pricing → and finally a financed, costed transition plan.

Most Thai issuers are not in TPI’s published universe of roughly 600 companies. Instead, LSEG runs the Management Quality assessment across roughly 15,000 companies using public disclosure alone. Two consequences follow:

• Your disclosure is the assessment. There is no analyst call, no questionnaire, no chance to explain. What is published — in English — is what is scored.
• Genuinely unassessed themes are dropped, not zeroed. A theme returned as not-applicable falls out of the average rather than dragging it down. The scoring damage comes from thin disclosure on themes where you are exposed, not from silence on ones where you are not.

The regulatory stack, 2026–2031.

Around the benchmark change, four regulatory tracks converge on the same reporting teams. Dates for the TSRS phase-in reflect the SEC’s published direction and hearing documents; final notifications were still pending gazettal at the research cut-off — treat them as planning dates, not filed law.

The stack is sequenced so that a SET50 company’s FY2026 report is simultaneously its first TSRS filing, its first FTSE-scored English disclosure, and its last ThaiESG-eligible SET-rated year. Mid-caps get more runway on the mandate — but none on the benchmark, which scores everyone from 2026.

Verification by the numbers.

Assurance is the top rung of every scoring ladder in this report, and Thailand’s de-facto verification route is the TGO Carbon Footprint for Organization (CFO) certification. Othello analysed the full public TGO registry on 11 July 2026. The headline numbers:

Three readings of that data:

• The market is moving fast — but from a low base. A 71% national surge in 18 months still leaves roughly four in five listed companies without current TGO certification, two reporting cycles before limited assurance becomes mandatory for the first cohort.
• Lapsed ≠ inactive, and absent ≠ absent. Fifty-two listed companies let certification lapse within the year — most are renewal candidates, not dropouts. And several mega-caps show no current TGO cert because they verify under ISO 14064-3 outside the Thai Carbon Label scheme entirely. Registry absence is a signal to investigate, not a verdict.
• The advisory bench is engineering-shaped. Thailand has 387 registered CFO consultants, overwhelmingly LCA and engineering practices. Verification capacity exists; what the market lacks is anyone coupling certification with investor-grade bilingual disclosure — the part that actually earns the score.

Timing note: TGO approves certifications in six rounds a year — the remaining 2026 rounds fall on 11 August, 14 October and 8 December — and the practical buying season runs Q4–Q1, ahead of the March One Report filing wave.

The six-rung disclosure ladder.

Across FTSE’s TPI staircase, CDP’s D-to-A model and the ISSB’s architecture, the same maturity ladder repeats. Each rung is a disclosure artefact — and each one a Thai issuer skips is points left on the table.

Where Thai disclosure actually falls

The recurring gaps we see across Thai reports map to the ladder’s upper rungs: only around 18% of rated Thai issuers track Scope 3 in any category; scenario analysis is thin or narrative-only; targets are announced without pathways or base years; board climate governance is asserted rather than evidenced with records; and assurance remains the exception. Every one of these is a writing-and-evidence problem before it is an operations problem.

Sector scorecards: exposure sets the bar.

Under FTSE’s exposure logic, the same disclosure earns different scores in different sectors. A professional-services firm disclosing verified Scope 1 & 2 with a target can score well; a transport operator with identical disclosure scores poorly, because its exposure demands more. The table condenses what each SET industry group is scored against. Exposure tiers are grounded inference from FTSE’s public methodology — the full exposure matrix is proprietary.

The financed-emissions chapter.

Thai banks and insurers face the most technically distinct climate assessment on the exchange. Their own operational footprint is small — the climate materiality sits in the portfolio, where financed emissions typically dwarf operations by orders of magnitude. The assessment stack reflects that:

• Measurement: PCAF. Financed emissions are Scope 3 Category 15, measured under the PCAF standard with its 1–5 data-quality scoring. Nine of the ten major Thai banks already use PCAF — the differentiator now is data quality and sector coverage, not adoption.
• Assessment: TPI’s banking framework. Rather than heavy-emitter pathways, financial institutions are assessed against the Net Zero Banking Assessment Framework — 10 areas and roughly 77 indicators covering targets, sector policies, disclosure and governance.
• Standards: IFRS S2 B58–B63. Financed emissions are an explicit disclosure requirement for commercial banking, insurance and asset management. The ISSB’s December-2025 reliefs matter for scoping: facilitated emissions and insurance-associated emissions are not required, and derivatives may be excluded.
• Targets: SBTi FINZ v1.0 (July 2025) sets the financial-sector net-zero standard — including fossil-fuel phase-out expectations and a transition deadline in December 2026 for institutions on the old framework.
• The Thai layer: Bank of Thailand’s Standard Practice guidance (2023), the Thailand Taxonomy — Phase 2 (May 2025) extended it to agriculture, manufacturing, construction and waste with a green/amber/red system — and NGFS membership with pilot climate stress-testing.

Leading Thai banks have set the local bar: net-zero own operations around 2030, financed-emissions net-zero by 2050, SBTi-validated interim targets, sector decarbonisation pathways and nine-figure green-finance commitments. For the rest of the sector, the FY2026–2027 disclosure question is no longer whether to publish a PCAF baseline — it is whether the published baseline, sector targets and taxonomy alignment read credibly in English to a global assessor.

The bilingual gap: the scored surface.

Every chapter so far lands on the same operational fact: from 2026, the document that earns a Thai company’s ESG score is its public English disclosure. The Thai 56-1 One Report remains the legal filing — authoritative for the SEC, structured by a fixed clause architecture. But the assessor at LSEG reads the English edition.

That creates a failure mode Thai issuers rarely price: clause drift. The English “translation” merges sections, softens numbers, drops methodology tags, or lags a revision cycle behind the Thai. To a regulator, inconsistency between editions reads as disclosure risk. To a rater running a staircase assessment off public text, a missing sentence is a missing rung — the TPI indicator for, say, board oversight or methodology citation simply fails, regardless of what the Thai edition says.

The 2026–27 action calendar.

Method, sources & caveats.

Method. This report synthesises: (1) Othello’s structured analysis of the public TGO Carbon Footprint registry, extracted 11 July 2026, cross-referenced against the ~940 SET- and mai-listed companies we track; (2) published FTSE Russell and TPI methodology documents; (3) SEC Thailand One Report requirements and TSRS hearing materials; (4) ISSB standards and December-2025 amendments; (5) PCAF, SBTi (incl. FINZ v1.0) and Thailand Taxonomy Phase 2 documentation; and (6) SET/LSEG announcements on the FTSE Russell transition and FTSE4Good Thailand Index.

Caveats — read these. FTSE Russell’s exact TPI-to-score blend formula and full sector-exposure matrix are proprietary; sector tiers in Chapter 6 are grounded inference, not published weightings. TSRS phase-in dates reflect SEC direction but final notifications were pending gazettal at the research cut-off; the Climate Change Act awaits enactment. The ~18% Scope 3 figure reflects rated-universe tracking estimates. Nothing here is legal, investment or assurance advice; verify against primary sources for your filing year.

Citation. Othello International, The State of Thai Corporate Climate Disclosure 2026, first edition, Bangkok, July 2026. Licensed for internal circulation with attribution.