The Fifteen Scope 3 Categories, and the Sixteenth That Does Not Exist Yet

Scope 3 has fifteen categories. Most published lists garble at least two of them, usually by dropping a parenthetical or losing the upstream and downstream prefixes that distinguish otherwise identical names. Here they are as the GHG Protocol itself names them, followed by the sixteenth category that is currently a draft proposal and not yet anything at all.

The fifteen categories, verbatim

Upstream, categories 1 to 8:

1. Purchased goods and services
2. Capital goods
3. Fuel- and energy-related activities (not included in scope 1 or scope 2)
4. Upstream transportation and distribution
5. Waste generated in operations
6. Business travel
7. Employee commuting
8. Upstream leased assets

Downstream, categories 9 to 15:

1. Downstream transportation and distribution
2. Processing of sold products
3. Use of sold products
4. End-of-life treatment of sold products
5. Downstream leased assets
6. Franchises
7. Investments

Three pairs are distinguished only by a single word and are the ones most often conflated: categories 4 and 9 differ only as upstream and downstream transportation and distribution, and categories 8 and 13 only as upstream and downstream leased assets. Category 3 carries a parenthetical that is part of its name, not a gloss: the exclusion of anything already counted in scope 1 or scope 2 is what stops double counting across the inventory.

A distinction that trips people up: is Scope 3 optional?

In the GHG Protocol Corporate Standard, the 2004 revised edition, scope 3 is described as "an optional reporting category that allows for the treatment of all other indirect emissions", and the standard requires only that companies "shall separately account for and report on scopes 1 and 2 at a minimum".

That wording is frequently quoted as though it settles the question. It does not. It is true of the Corporate Standard and nothing else. The separate Corporate Value Chain (Scope 3) Standard of 2011 sets requirements for companies reporting a scope 3 inventory, and the ISSB's IFRS S2 requires scope 3 disclosure in its own terms, subject to a first-year relief. So whether scope 3 is optional depends entirely on which instrument a company is reporting under, and anyone quoting the 2004 sentence to a client without that qualification is giving incomplete advice.

The sixteenth category does not exist yet

A revision of the Scope 3 Standard is under way, and it proposes two changes that are widely discussed as though they were settled. They are not.

The proposals would narrow category 15 so that only investments fall within it, moving insurance and underwriting activities to a new category 16 for other value chain activities, proposed as optional except for oil and gas distributors. The same draft would require reported scope 3 data to be disaggregated into tiers by data type, and would require companies to state whether their scope 3 figures were third-party verified.

The GHG Protocol's own progress update carries the clearest possible warning on its status: "This is not a GHG Protocol Standard; all content is draft and subject to change", and the revisions "should not be construed as final or relied upon as advice". The draft text remains subject to revision and approval before it even reaches public consultation.

The published timeline puts a consolidated draft standard out for public consultation in an estimated second quarter of 2027, with a revised standard published in an estimated fourth quarter of 2028. That revision will merge the Corporate Standard, the Scope 2 Guidance and the Scope 3 Standard into a single Corporate Standard version 3.0, in a joint process with ISO. So the fifteen categories above are the ones to work to for the next two reporting cycles at least.

One amendment that is real, and narrower than it sounds

Separately from the GHG Protocol revision, the ISSB issued targeted amendments to IFRS S2 on 11 December 2025. These are often summarised as a general scope 3 relief and a general industry-classification relief, and both descriptions overstate them.

The scope 3 relief permits an entity to limit measurement and disclosure of category 15 emissions to financed emissions as IFRS S2 defines them. The classification relief permits alternative systems to the Global Industry Classification Standard specifically for disaggregating financed emissions information. There are also jurisdictional reliefs relating to the use of the GHG Protocol standard and to global warming potential values.

Crucially, the amendments are effective for reporting periods beginning on or after 1 January 2027, with early application permitted. A company reporting for 2026 is not operating under them unless it has chosen to.

Where the difficulty actually sits

The GHG Protocol's own survey of stakeholders put supplier data at the centre: "collecting supplier-specific emissions data is the biggest challenge for organizations", compounded by "paywalled life cycle inventory emission factor databases" and consequent reliance on spend-based factors from input-output models.

On assurance, the survey found views divided rather than settled. Some respondents said that "compiling audit-quality emissions results for most of the value chain is not possible beyond direct vendors" and that verification across thousands of partners "is currently not feasible". Others argued for stronger assurance requirements aligned to mandatory disclosure rules. Reporting only the first half of that, as most commentary does, misrepresents the Protocol's own evidence.

For finance teams, the practical consequence is that category 1 and category 11 usually dominate the inventory while being the hardest to evidence, and the data-quality tiering in the draft revision is aimed squarely at that problem.

Where this fits

Our guide to carbon accounting and Scope 3 emissions for finance teams covers the measurement approach, and our guide to IFRS S1 and S2 against the ESRS covers the disclosure frameworks the figures feed into. For a practical half-day treatment with worked examples, see our carbon accounting CPD course covering the GHG Protocol, TCFD and TNFD.

Every category name above is quoted from the Corporate Value Chain (Scope 3) Standard as published by the GHG Protocol, and the draft proposals from its own phase 1 progress update. Check the current status before advising, since the revision timeline has already moved once.