Scope 3 has long been the soft underbelly of corporate carbon accounting. The combination of CSRD's first wave of reports (FY2024, published 2025), the SBTi FLAG target-setting requirements, and the March 2026 update to the GHG Protocol Land Sector and Removals Standard (LSRS) has closed the window on spend-based proxies as an acceptable default in material categories [1][2].
What changed concretely
CSRD / ESRS E1. Under ESRS E1, in-scope undertakings must disclose Scope 3 emissions across all 15 GHG Protocol categories that are material, with explicit disclosure of methodology, data sources, and the proportion of activity data that is primary versus secondary. The materiality test for food, agriculture, and consumer goods companies almost always pulls Category 1 (Purchased Goods and Services) and Category 11 (Use of Sold Products) into mandatory disclosure.
SBTi FLAG. Companies in scope of FLAG (forestry, agriculture, land use sectors above a revenue or emissions threshold) must set FLAG targets covering ≥67% of forestry-, land- and agriculture-related emissions, and must commit to no-deforestation by 31 December 2025 [3]. The 2026 FLAG guidance update aligned with the GHG Protocol LSRS clarifies removals accounting, land-tracking, and the treatment of insets [1].
GHG Protocol LSRS. The Land Sector and Removals Standard, finalised in March 2026, formalises separate reporting for gross emissions, gross removals, and biogenic carbon transfers. For agri-food supply chains this means inventories must trace activity down to land parcels where possible — a step change from the previous category-average emission-factor approach [1].
What 'primary data' actually means in practice
Primary supplier data is not synonymous with supplier-reported numbers. Audit-grade primary data has four properties: (a) it is supplier-specific (not industry-average); (b) it is activity-based (kg, kWh, hectares — not spend); (c) it carries documented emission factors and calculation methodology; and (d) it is verifiable to source records. CSRD assurance — limited assurance from FY2024, with the trajectory toward reasonable assurance — applies the same evidentiary standard to Scope 3 disclosures that it applies to financial line items.
Implementation pattern
Most corporates we work with land on a three-tier hierarchy: (1) primary supplier data for top-decile-by-emissions suppliers in material categories; (2) sector-specific secondary factors (e.g. ecoinvent, Agribalyse) for the long tail; (3) spend-based residual estimates only for immaterial categories, clearly flagged. The transition cost is dominated by supplier engagement and data plumbing, not by accounting methodology.
Where CAS fits in
CAS supports corporates and their auditors on the engineering and methodology layer of Scope 3: (a) materiality and methodology-tier strategy aligned to ESRS E1, GHG Protocol Corporate Standard, and the LSRS; (b) supplier data-collection pipelines with audit-grade lineage; (c) Category 1 and Category 11 deep-dives including PCF and EPD-grade product-level inventories; and (d) SBTi FLAG inventories and target-setting packs. We are an independent consultancy; we do not provide assurance under CSRD.
Sources
[1] SBTi, 'What companies need to know: SBTi updates the FLAG Target-Setting Guidance and the GHG Protocol's Land Sector & Removals Standard', March 2026.
[2] Klimato, 'How CSRD, Scope 3, and SBTi Work Together', November 2025.
[3] SBTi, 'Why No-Deforestation Must Be a Priority: SBTi's FLAG Guidance Unpacked', March 2025.