Scope 3 Data Collection in 2026: From Voluntary Exercise to Mandatory Disclosure Requirement
Key Takeaways
- Scope 3 emissions measurement is transitioning from a voluntary best-practice exercise to a mandatory disclosure requirement under UK SRS S2, SBTi V2.0, and CSRD for companies with EU obligations
- For most companies, Scope 3 represents 70–90% of total emissions, making it the most material and most challenging element of carbon reporting
- Data quality ranges from spend-based estimates (lowest quality) through activity-based calculations to supplier-specific data (highest quality), and companies should develop a multi-year roadmap to improve quality progressively
- The most material Scope 3 categories for UK companies are typically Category 1 (purchased goods and services), Category 11 (use of sold products), and Category 15 (investments) for financial institutions
- Building a repeatable annual Scope 3 process — not a one-off calculation — is essential for regulatory compliance and assurance readiness
Why Scope 3 Is Now Mandatory
Three converging forces are making Scope 3 reporting mandatory for UK companies:
- UK SRS S2: The FCA’s September 2026 policy statement confirms that listed companies must disclose Scope 3 emissions from financial years beginning January 2028. While comply-or-explain provisions apply to specific categories, the expectation is comprehensive coverage
- SBTi V2.0: The revised Corporate Net-Zero Standard requires Scope 3 targets covering at least 95% of total Scope 3 emissions. Companies revalidating existing targets must meet this threshold
- Supply chain cascade: Large companies subject to UK SRS and CSRD are requesting Scope 3 data from their suppliers, creating indirect but powerful reporting obligations throughout value chains
The era of “Scope 3 is too hard to measure accurately, so we don’t report it” is definitively over.
The 15 Categories: Prioritisation for UK Companies
The GHG Protocol defines 15 Scope 3 categories. Not all are equally material for every company. UK companies should prioritise based on emission magnitude and data availability:
Typically Largest Categories
- Category 1 — Purchased goods and services: Usually the single largest Scope 3 category (40–70% of total Scope 3 for manufacturers, retailers, and service companies). Covers emissions from producing everything the company buys
- Category 11 — Use of sold products: Dominant for companies selling energy-consuming products (vehicles, appliances, electronics, gas boilers)
- Category 15 — Investments: The largest category for financial institutions (banks, asset managers, insurers). Covers financed emissions across lending and investment portfolios
Commonly Significant Categories
- Category 3 — Fuel and energy-related activities: Upstream emissions from purchased electricity, heat, and fuels (not already in Scope 1 or 2)
- Category 4 — Upstream transportation: Emissions from transporting purchased goods from suppliers to the company
- Category 6 — Business travel: Air, rail, and road travel by employees. Often small in absolute terms but high visibility
- Category 7 — Employee commuting: Emissions from employees travelling to and from work
- Category 12 — End-of-life treatment: Emissions from disposal or recycling of products sold
Data Quality Hierarchy
The GHG Protocol recognises a hierarchy of data quality for Scope 3 calculations. Companies should aim to improve quality over time:
Level 1: Spend-Based (Lowest Quality)
Multiply the monetary value of purchased goods/services by sector-average emission factors per unit of economic output. Data source: procurement spend data from accounts payable systems. Emission factors: DEFRA, Exiobase, EEIO databases.
Advantages: Uses readily available financial data. Can cover all categories quickly.
Limitations: Highly approximate. Does not reflect actual supplier performance. Inflation distorts results year-on-year.
Level 2: Activity-Based (Medium Quality)
Multiply physical activity data (tonnes purchased, kWh consumed, km travelled) by product-specific emission factors. Data source: procurement systems, logistics data, travel booking systems.
Advantages: More accurate than spend-based. Reflects actual quantities rather than costs.
Limitations: Emission factors are still averages, not supplier-specific. Requires more granular procurement data.
Level 3: Supplier-Specific (Highest Quality)
Use emissions data provided directly by suppliers for the specific goods or services purchased. Data source: supplier sustainability reports, CDP responses, or direct data requests.
Advantages: Most accurate. Reflects actual supplier decarbonisation efforts. Enables meaningful target-tracking.
Limitations: Requires supplier engagement and capacity. Data availability varies widely. Verification challenges.
Supplier Engagement Strategies
Moving from spend-based to supplier-specific data requires structured supplier engagement:
- Prioritise by materiality: Focus supplier engagement on the top 20–50 suppliers by spend or emission contribution. For most companies, 80% of Scope 3 emissions come from fewer than 20% of suppliers
- Use standard templates: Provide suppliers with a clear, simple data request template. The CDP Supply Chain programme, WBCSD PACT Pathfinder, and SBTi Supplier Engagement guidance all offer standardised formats
- Embed in procurement: Include carbon data requirements in procurement specifications and supplier selection criteria. This shifts the conversation from “can you provide data?” to “data provision is a condition of doing business”
- Support supplier capacity: Many SME suppliers lack the expertise to calculate their own emissions. Consider providing training, tools, or co-funded carbon accounting support
- Accept progressive improvement: Not every supplier will provide perfect data in year one. Accept estimates where necessary, but track improvement over time
Dealing with Data Gaps
Data gaps are inevitable in Scope 3 reporting. The key is to be transparent about gaps and demonstrate a plan to close them:
- Document methodology choices: For each category, document whether you used spend-based, activity-based, or supplier-specific data, and why
- Disclose data quality: UK SRS and SBTi both expect companies to disclose the proportion of Scope 3 emissions calculated using each methodology tier
- Estimate conservatively: Where data is unavailable, use conservative estimates (higher emission factors) rather than omitting the category entirely
- Set improvement targets: Commit to specific data quality improvements (e.g., “move Category 1 from spend-based to activity-based by 2028”)
Building a Repeatable Annual Process
Regulatory compliance requires Scope 3 to be measured consistently year after year, not as a one-off project. Essential elements of a repeatable process:
- Data governance: Assign ownership for each Scope 3 category to a specific team (procurement for Category 1, travel management for Category 6, treasury for Category 15)
- System integration: Connect carbon accounting software with ERP, procurement, travel, and logistics systems to automate data flows
- Annual calendar: Establish a fixed annual cycle: data collection (Q1), calculation (Q2), verification (Q3), disclosure (Q4)
- Base year management: Maintain a consistent base year and update it when significant structural changes occur (acquisitions, divestments, methodology changes)
- Internal audit trail: Maintain documentation sufficient for external assurance — every number should be traceable to a source
Limited Assurance Readiness
UK SRS will require limited assurance of emissions data from the second year of reporting. For Scope 3, assurance readiness means:
- Clear documentation of methodology, assumptions, and emission factors used
- Evidence trails linking reported figures to source data
- Defined processes for data quality checks and internal review
- Reasonable estimates where actual data is unavailable, with documented rationale
Need Help with Scope 3 Data Collection?
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