Singapore Scope 3 Reporting: What STI Companies Should Prepare for FY2026

The financial year you'll be reporting on has already started. For STI constituents on a calendar year, FY2026 is more than half spent, which means the Scope 3 data you'll disclose is being generated right now, in invoices being paid and shipments being booked, whether or not anyone is capturing it.

That's the uncomfortable arithmetic of value chain emissions. Scope 1 and 2 can be reconstructed after the fact from utility bills and fuel records. Scope 3 often can't, because the data sits inside other companies who have no obligation to keep it for you and no reason to prioritise your request. If your supplier engagement programme starts when the year ends, you will be reporting estimates.

Singapore's top 30 listed companies are the first in the country to face this as a mandate. Here's what the requirement actually is, and what the preparation involves.

The Requirement, Precisely

On 25 August 2025, ACRA and SGX RegCo extended most of Singapore's climate reporting timelines. Scope 3 for STI constituents was not among them.

The current position for listed companies:

Two details worth pinning down, because they get misreported.

The STI cohort is frozen. The Scope 3 obligation applies if a company was an STI constituent on 30 June 2025, and it continues to apply even if the company subsequently drops out of the index. Falling off the STI does not release you. Conversely, joining the index after that date doesn't pull you in on this timeline.

Assurance is FY2029, not FY2027. A number of guides still cite FY2027 for external limited assurance; that was the position before the August 2025 announcement, which deferred it to FY2029 for all listed companies. And note what assurance covers when it arrives: Scope 1 and 2. Scope 3 assurance isn't on the published timetable at all yet.

The regulators were explicit about why STI companies kept their date. Their reasoning was that STI constituents have demonstrated higher readiness and capability, and larger companies with more resources should lead. That framing matters for how the first reports will be read, this cohort was singled out as the group that could handle it.

What You Actually have to Measure

Singapore's rules run through the SGX Listing Rules, which require climate disclosures in accordance with IFRS S2. For Scope 3, that means measurement in line with the GHG Protocol Corporate Standard, and consideration of the fifteen Scope 3 categories set out in the GHG Protocol Corporate Value Chain (Scope 3) Standard.

The word "consider" is doing important work. You are not required to report all fifteen categories. You are required to consider all fifteen, determine which are relevant to your business, and disclose which ones you've included. Excluding a category is a legitimate outcome of that analysis, but it's a disclosed, reasoned exclusion, not a silent omission. Deciding that purchased goods and services is immaterial to a manufacturer would need a very good explanation.

There are also transition reliefs available in the first year of applying the IFRS Sustainability Disclosure Standards, which STI companies should confirm they've mapped against their own reporting position rather than assuming either that they apply or that they don't.

The Data Problem, Honestly Stated

Scope 3 typically accounts for the large majority of a company's footprint, commonly cited at around 70% or more of total emissions, and in supply-chain-heavy sectors substantially higher. It is also the only part of the inventory you cannot calculate from your own records.

The core difficulty isn't supplier reluctance. Most suppliers, asked politely, will try. The problem is that many of them, particularly smaller manufacturers, logistics providers and agricultural producers, simply don't have systems that produce emissions data in the format, granularity and documentary trail that a reviewer would accept. You ask for a product carbon footprint; you get a number in an email with no method behind it.

That leaves most companies leaning on spend-based estimation: multiply what you spent by an emission factor for that category of spend. It's a legitimate starting method and it's how nearly everyone begins. But it has two known weaknesses. It's insensitive to actual supplier performance, a supplier who decarbonises aggressively produces exactly the same number as one who doesn't, as long as your invoice is the same. And it produces wide uncertainty bands that become uncomfortable once anyone starts checking.

The direction of travel is away from it. The GHG Protocol published a Phase 1 progress update on its Scope 3 Standard revision on 31 March 2026, the first substantive rewrite signal since 2011, and explicitly draft material subject to change. The proposals point clearly at higher expectations: a 95% minimum coverage floor with exclusions requiring justification, disaggregation of data by quality tier with spend-based proxies ranked lowest, disclosure of whether data is verified, and a new Category 16 for facilitated value chain activities. A full public consultation draft is expected around mid-2026, with the final standard targeted for late 2027. None of it binds you for FY2026. All of it tells you where the bar is heading.

A Workable Sequence for the Data

The teams that manage this well tend to follow roughly the same order.

Screen first, then go deep. Run a spend-based or otherwise rough estimate across all fifteen categories to find out where your emissions actually sit. Nearly every company finds concentration, a handful of categories carrying most of the footprint. That screening result is what tells you where to spend your limited supplier-engagement effort. Trying to collect primary data everywhere at once is the most common way to fail.

Segment suppliers by materiality and readiness. Cross your emissions hotspots against which suppliers can actually respond. Some already report emissions and will hand you usable figures. Some could with a template and a phone call. Some cannot, this year, at any price. Treat those three groups differently rather than sending an identical questionnaire to all of them.

Standardise the ask. One template, one set of definitions, one boundary specification, one deadline. Suppliers dealing with several listed customers are receiving different formats from each and answering none of them well. Precision about what you're asking for, which emissions, for which period, calculated how, improves what comes back more than persistence does.

Keep the estimates you can't replace, but label them. Where primary data doesn't exist, estimate, document the method, and record it as an estimate. A clearly-labelled estimate with a defensible methodology is a perfectly respectable disclosure. An estimate presented as though it were measured is a problem waiting to surface.

Build the improvement plan into the first report. Because the coverage will be imperfect in year one, what distinguishes a credible disclosure is showing you know where the gaps are and how you intend to close them. That's a stronger position than an artificially tidy number.

Controls: Treat it Like Financial Data

This is where the FY2029 assurance date does more work than its distance suggests.

Scope 3 isn't in the assurance scope even then, only Scope 1 and 2 are. But the internal disciplines are the same, and the data architecture you build for Scope 3 now is the one you'll be defending later. More immediately: these figures sit in a public disclosure made under the Listing Rules, with the reputational and regulatory exposure that implies, regardless of whether an assurer signs them.

The controls that matter are unglamorous:

Named ownership per category. Someone owns Category 1, someone owns Category 6, and it isn't the same overworked sustainability analyst for all fifteen. Categories map to functions, procurement, logistics, HR, facilities, and ownership should follow.

Written methodology. For each category: what data source, what emission factor set, which calculation approach, what assumptions, what boundary. If the person who built the model leaves, the number should still be reproducible.

Traceability to source. Every figure should trace back to something, a supplier submission, an ERP extract, a spend report, a logistics record. Spreadsheets assembled by hand, without version control or an audit trail, are the single most common weakness.

Consistency of definitions across the group. Multi-entity groups routinely find that "business travel" or "purchased goods" means different things in different subsidiaries. Fix the definitions before you consolidate, not after.

Year-on-year comparability. You'll restate. Everyone does, as data quality improves. Plan for it: record what changed, why, and what the prior-year figure would have been on the new basis.

Where this Leaves Non-STI Companies

Formally, Scope 3 remains voluntary for non-STI listed companies until further notice, and for large non-listed companies too. Practically, that's less of a reprieve than it reads.

When thirty of Singapore's largest companies need value chain data, the requests flow directly to their suppliers, including plenty of smaller listed and private companies with no disclosure obligation of their own. Being unable to answer credibly is increasingly a commercial issue rather than a compliance one, as buyers fold emissions data into sourcing decisions. Non-STI issuers also have their own deadlines approaching: full ISSB-based climate disclosures from FY2028 for those above S$1 billion market cap, FY2030 below it, and limited assurance for everyone at FY2029.

Worth knowing: the Sustainability Reporting Grant, administered by EDB and Enterprise Singapore, exists to help companies build reporting capability, and its application deadlines were revised in line with the August 2025 timeline changes. If you're building Scope 3 capability ahead of a mandate, check whether you qualify.

The Realistic View of Year One

The baseline is sobering. EY's third Transparency in Focus study with CPA Australia looked at the 359 Singapore-listed companies publishing sustainability reports for the year ended 31 December 2024. Almost all, 98%, made at least one climate disclosure, but only 32% covered all eleven TCFD recommendations, the framework IFRS S2 builds directly on. Large caps did better, at 60%, against 35% of mid caps and 25% of small caps. A separate review by SGX RegCo and the National University of Singapore, covering 529 issuers, found only around 29% reporting Scope 3 emissions at all.

STI constituents sit at the strong end of that distribution, but even there, four in ten hadn't yet covered the full TCFD set, and Scope 3 was a minority practice market-wide. The distance between reporting Scope 1 and 2 competently and reporting fifteen categories of value chain emissions is considerable.

Which is worth saying plainly: the first Scope 3 disclosures will not be precise, and they aren't expected to be. Coverage will be uneven, estimation will be heavy in places, and restatements will follow. That is normal for a first cycle everywhere this has been introduced.

What separates a good first report from a poor one isn't accuracy. It's whether the company can show it understands its own value chain, where the emissions concentrate, which data it has, which it doesn't, how it estimated the rest, and what it's doing to improve. That's a story you can only tell if you started collecting before the year ended.

Preparation Checklist

1. Confirm STI constituent status as at 30 June 2025, the obligation persists even if you've since left the index.

2. Screen all fifteen Scope 3 categories to identify which are relevant and where emissions concentrate; document the reasoning for any exclusions.

3. Check which IFRS S2 first-year transition reliefs apply to your position.

4. Segment suppliers by emissions materiality and data readiness, and engage each group differently.

5. Standardise one data request template, same definitions, boundary, period and deadline for everyone.

6. Assign named ownership for each material category to the function that holds the data.

7. Document methodology per category: source, emission factors, calculation approach, assumptions.

8. Label estimates as estimates, and retain the basis for each.

9. Make every figure traceable to a source record; get the calculation out of unversioned spreadsheets.

10. Plan for restatement, record what changes and why, so year two remains comparable.

11. Draft the improvement plan alongside the disclosure; gaps disclosed with a remediation path beat gaps concealed.

12. Note FY2029 limited assurance on Scope 1 and 2, and build Scope 3 controls to the same standard now.

Position as of July 2026, reflecting ACRA and SGX RegCo's announcement of 25 August 2025 and the SGX Listing Rules as amended. The GHG Protocol's Scope 3 Standard revision remains in draft. Confirm current requirements against ACRA, SGX RegCo and the SGX Rulebook, and take professional advice on your company's circumstances.

Sources

ACRA and SGX RegCo, SGX Rulebook, IFRS Foundation, Allen & Gledhill, Slaughter and May, Persefoni, Anthesis, Zuno Carbon, Keslio, Speeki, Presgo, Environment+Energy Leader, GHG Protocol, EY Singapore, The Edge Singapore, Certainty Software, Enterprise Singapore

This article is intended for general professional information and does not constitute legal, financial, or investment advice.