Measuring your supply chain emissions and producing a CSRD ready disclosure are two different jobs, and the second one is where most programmes stall.
A number in a spreadsheet is not a disclosure. Under CSRD you have to justify why you reported that category at all, explain the boundary you drew, evidence the method you used, disclose which reliefs you relied on, and hand the whole thing to an assurance provider who will ask where each figure came from.
The good news is that 2026 brought real simplification. The less good news is that the rules changed twice, and a lot of the guidance still in circulation describes a framework that no longer exists.
Before Anything Else, Confirm Which Rulebook Applies
Scope narrowed considerably. Omnibus I, Directive (EU) 2026/470, entered into force on 18 March 2026 and raised the CSRD entry test to more than 1,000 employees and at least €450 million net turnover, both tests, consolidated at parent level, applying to financial years beginning on or after 1 January 2027.
The standards were rewritten. On 3 July 2026 the European Commission adopted the delegated act containing the revised ESRS, cutting mandatory datapoints by roughly 60%, alongside a second delegated act establishing the voluntary standard for smaller undertakings. Both remain subject to European Parliament and Council scrutiny. Double materiality survives.
For financial year 2026 there are three routes, and you must state in the report which you took:
- Apply the existing ESRS.
- Adopt the revised ESRS early, in full.
- Apply the existing ESRS but take specific reliefs from the revised standards, such as the top down materiality approach and the value chain limitations.
For UK organisations, two paths lead here. Either you are a UK subsidiary sitting inside an in scope EU parent’s consolidated statement, in which case you receive the data request rather than file the report. Or you are a UK parent caught by the third country route, above €450 million of EU turnover with a large EU subsidiary or branch, reporting on financial year 2028. Note that this second group will report under a separate set of standards for non-EU parent undertakings, which the Commission has said it will address later. If that is you, build the data and watch that space.
Step One: Draw The Boundary Before You Count Anything
Two boundaries matter, and getting them wrong is the most expensive mistake available.
The organisational boundary. The revised ESRS are more flexible here. Financial control remains the starting point, in line with the GHG Protocol, but operational control or equity share can be used instead. That flexibility exists for a practical reason: it lets you align your ESRS emissions boundary with the one you already use for group reporting or IFRS sustainability disclosures.
Take the option. One boundary across CSRD, SECR, UK SRS and any SBTi submission means one set of numbers to defend. Different boundaries for different frameworks means an annual reconciliation exercise nobody enjoys and auditors always notice.
The value chain boundary. Which entities, tiers and geographies sit inside your Scope 3 inventory. Document the logic, because it will be tested.
Step Two: Map The 15 Categories Against Materiality, Not Ambition
Under the GHG Protocol Corporate Value Chain Standard, Scope 3 splits into 15 categories, eight upstream and seven downstream. Under CSRD, what you disclose is gated by your double materiality assessment rather than by completeness for its own sake.
That distinction matters. Work through every category, record a materiality conclusion for each, and keep the reasoning. The revised standards also add a relief allowing activities to be excluded from metric calculations where they are not a significant driver of the relevant impacts, risks or opportunities and exclusion would not impair faithful representation. If you use it, you disclose that you used it.
One caution worth building for now. The GHG Protocol is separately revising the Scope 3 Standard, and its March 2026 progress update proposes a completeness floor requiring at least 95% of required Scope 3 emissions to be accounted for, with exclusions quantified and justified. That is draft, the 2011 standard still applies, and a final version is targeted for late 2027. But the two frameworks are pulling in slightly different directions, one toward materiality gating and the other toward completeness. Record your emissions and your exclusions in a way that can serve either, and you will not be rebuilding in 2028.
Step Three: Know What You Can Actually Ask Suppliers For
This is the change most teams have not yet absorbed, and it should reshape your supplier questionnaire.
Omnibus I introduced a value chain cap. Companies in CSRD scope cannot require value chain partners with 1,000 employees or fewer to provide more sustainability information than the voluntary standard requires. Three details make this practically important:
- The cap covers disclosures marked as necessary in the voluntary standard’s basic and comprehensive modules. It does not extend to items marked voluntary, or necessary if applicable.
- It applies to non-EU partners too. For UK suppliers to EU groups, that is a genuine protection.
- It does not cover gross Scope 1, 2 and 3 greenhouse gas emissions. The GHG metrics are carved out.
That last point is the one to underline. You can still ask your small suppliers for their emissions figures. What you cannot do is bury that request inside a forty page ESG questionnaire covering workforce, biodiversity and governance and expect it to be enforceable.
The practical response is to split your supplier data request in two. A short, mandatory emissions request that survives the cap. And a separate, clearly voluntary section for anything else, framed as a request rather than a requirement. Response rates tend to improve when suppliers can see which is which.
The cap applies from financial year 2026, so this is a live design decision for the questionnaire going out this year.
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Step Four: Choose A Calculation Method Per Category, And Disclose It
There are three broad approaches to calculating supply chain emissions, and a mature inventory uses all of them in different places: spend based for the long tail, activity based using recognised factor sets such as the UK Government conversion factors for the middle, and supplier specific primary data for the categories and suppliers that dominate your footprint. Our explainer on Scope 3 emissions measurement covers the trade offs between the three in detail.
For CSRD purposes, the important addition is that the method itself becomes a disclosure. You report the approach, the significant assumptions, the proportion of the figure that rests on estimates, and how that is expected to change. Which means the choice needs to be deliberate and documented per category, not inherited from whoever built the first spreadsheet.
Two practical notes. Spend based figures are close to useless for showing progress, because two suppliers with identical invoices produce identical emissions regardless of how either performs. And any improvement in method changes your numbers, so you need a base year recalculation policy agreed in advance, or better data will look like worse performance.
Step Five: Build For Assurance From The First Data Point
CSRD disclosures are assured. That single fact should shape how you collect data all year.
What an assurance provider will want:
- The source document attached to the figure, not filed separately.
- The emission factor set and version used, recorded against each reporting year.
- Estimation methods documented at the time of estimating, with the reasoning.
- A change log showing who altered what, when and why.
- A per entity, per year record of which ESRS version you applied and which reliefs you relied on.
That final item is new and easy to overlook. With three possible routes for FY2026 and phased reliefs beyond it, your own choices become part of what you evidence. Track them deliberately rather than reconstructing them under time pressure.
Where Programmes Usually Go Wrong
- Counting before scoping. Boundary and materiality decisions first, always.
- One questionnaire for every supplier. The cap means a large supplier and a twenty person supplier now sit under different rules.
- Separate inventories per framework. CSRD, SECR, UK SRS and SBTi should draw on one set of numbers. Divergence is visible and hard to explain.
- Undocumented estimates. An estimate you can justify is fine. An estimate nobody can reconstruct is a finding.
- Waiting for the rules to settle. Thresholds and standards have moved repeatedly. The underlying data work has not changed at all, and it is the part that takes longest.
How Enistic Helps
Scope 3 emissions measurement for CSRD is mostly a data and evidence problem, which is exactly what our platform was built for. We develop and maintain it in house, which means it moves when the standards move, and 2026 has been a good demonstration of why that matters.
Practically, that means automated collection across multiple sites, entities and suppliers, cutting data collection effort by up to 80%, with the factor version, source document, calculation method and change history held against every figure so the inventory stands up when an assurance provider starts asking questions.
- 5,000+ compliant reports delivered.
- 100% compliance record, with no failures.
- 11.7% audit rate, against an industry average of 33%.
- 98% client renewal rate.
Our carbon consultants and auditors are all in house, and one is named to your account. They work on supplier engagement alongside your team rather than handing you a portal and a deadline, and it is covered by one simple monthly payment with unlimited expert support.
The teams that will find CSRD manageable are the ones treating supply chain emissions as a permanent data pipeline rather than an annual reporting scramble. Built once, properly, year two costs a fraction of year one.
Book a demo and we will map your Scope 3 categories against your materiality assessment, and show you which supplier data you actually need and are entitled to ask for.