IFRS S2 Scope 3: How to Assess All 15 Categories and Improve Data Quality

Scope 3 spans suppliers, logistics providers, employees, customers, leased assets, franchises and investments. No single internal system normally contains all relevant activity data. The temptation is therefore to ask business units which categories “feel relevant”, calculate a few easy numbers and describe the rest as unavailable. That approach does not establish a defensible value-chain boundary or a faithful measurement.

IFRS S2 instead requires a complete consideration of all 15 categories, use of reasonable and supportable information available without undue cost or effort, and a measurement framework that makes data-quality trade-offs visible. The practical goal is not perfect primary data in year one. It is a controlled inventory that records why a category is included or excluded, how the estimate was built, how much of it uses specific and verified data, and what will improve next.

Figure 1. All 15 Scope 3 categories and a controlled data-improvement roadmap. London Reporting Academy learning visual.

The category register is the core decision record. It prevents category decisions from being buried in separate workbooks and allows reviewers to trace the total Scope 3 figure back to the value-chain screen. A good register is maintained by reporting period and is connected to the entity, product, supplier, logistics, property and investment systems that support each category.

The value-chain boundary includes its breadth and composition: the upstream and downstream entities, activities and relationships that can affect the measurement. IFRS S2 requires reasonable and supportable information available at the reporting date without undue cost or effort. That information can include procurement and sales data, logistics flows, customer use patterns, lease registers, franchise systems, investment books, sector research and supplier engagement.

The organisational boundary is applied first. Activities outside Scope 1 and Scope 2 can then enter Scope 3 in the appropriate category. This is especially important for leased assets, franchises and investments: the same physical source can move between scopes depending on ownership and control, but it should not be double counted within the reporting entity’s inventory.

Scope 3 is expected to include estimation. A useful distinction is between the activity data that represents what happened and the emission factor that converts the activity into greenhouse gas emissions. Both can be primary, secondary, specific, proxy, current, older, verified or unverified. The correct method is the one that faithfully represents the category using the best reasonable inputs for the entity’s circumstances.

IFRS S2 lists four identifying characteristics in no particular order. They are not a mechanical score in which one characteristic always wins. Management considers trade-offs. A verified industry average can be more reliable than an unverified supplier figure with a mismatched boundary. A slightly older technology-specific factor can be more representative than a recent generic global average.

A first-year inventory should be complete enough to support the disclosure objective, even when much of it uses estimates. Data-improvement resources are then directed to categories and segments where better information could change investor understanding, management decisions, risk assessment or target tracking. The category total alone is not the only prioritisation input.

IFRS S2 requires reassessment when a significant event or significant change in circumstances affects the value chain. Examples include a supplier change that alters emissions, an acquisition that expands the value chain, a business-model shift, outsourcing or insourcing, a new product use profile, or new emissions regulation affecting a supplier. More frequent reassessment is permitted and is often useful for annual controls.

Context. Meridian Manufacturing screens all 15 categories. Categories 1, 3, 4, 6, 7, 9, 11 and 12 are applicable; Categories 8, 13 and 14 are not applicable based on the approved lease and franchise registers; Category 15 contains a small treasury investment portfolio assessed separately. Category 1 initially represents 62% of estimated Scope 3 and is calculated almost entirely from spend factors.

Year-one decision. Meridian publishes a complete estimate using spend and average data, explains the category inclusions and data characteristics, and avoids claiming that the estimate is supplier-specific. It defines the Category 1 denominator as procurement spend excluding taxes and intra-group transactions and discloses that 8% of Category 1 uses supplier-specific product data and 12% of total Scope 3 inputs have been internally or externally verified.

Improvement plan. The company selects steel, aluminium, packaging and contract manufacturing for the first upgrade because they drive emissions, procurement decisions and transition exposure. It captures mass and specification data, obtains supplier product footprints with boundary checks, retains secondary data for the long tail, and sets annual coverage and verification milestones. A supplier-country shift and product redesign are added as reassessment triggers.

Context. Illustrative manufacturer using a mix of supplier-specific, activity-based and secondary data.

Why the wording is useful

Evidence needed

Approved category register for all 15 categories.

Value-chain population and denominator files.

Category calculation workbooks, factor sources and assumptions.

Supplier data and boundary/verification assessments.

Specific-activity and verified-input coverage calculations.

Data-gap and improvement register with owners and milestones.

Movement analysis separating activity, factor, boundary and method changes.

Management and governance approval record.

Practical consequence. A complete, clearly explained estimate is generally more useful than omitting large categories while waiting for perfect data.

Prerequisite: GHG Protocol and IFRS S2: Organisational Boundaries, Methods and Required Disclosures

Related metric: IFRS S2 Scope 2 Disclosure: Location-Based Emissions and Contractual Instruments

Financial-sector Category 15: IFRS S2 Category 15 and Financed Emissions: What Financial Institutions Must Report

Transition: IFRS S2 GHG Amendments 2025: What Changed and How to Prepare for 2027