CSRD introduced, for the first time, an EU-wide assurance requirement for sustainability reporting, so that in the European Commission's words the reported information is "accurate and reliable". It does not ask for a single emissions figure. Under ESRS E1, it asks you to disclose Scope 1, 2, and 3 emissions in a way that can be compared year over year and independently assured. Since the 2026 Omnibus revisions, that assurance stays at limited level, but it stays mandatory.
Limited assurance is not a rubber stamp. An external auditor has to conclude your data is free from material misstatement, so they need an evidenced basis for every number. That comes down to three things: a traceable path from source document to reported figure, documented emission factors, and consistent boundaries year over year.
Spend-based accounting was built to answer "roughly how much," not "where does this come from." You take total spend in a category, apply an average factor, and multiply. Fast, low-effort, useful for a rough baseline. It falls apart the moment someone asks for the receipt.
A spend-based figure describes a category, not a purchase. It cannot tell you which supplier drove emissions up, or whether switching suppliers lowered your footprint, because the number moves with spend, not with what was delivered. When spend shifts for reasons unrelated to emissions, like price inflation or a one-off order, the footprint shifts with it. That is the kind of unexplained swing auditors notice.
Audit-ready does not mean perfect. It means traceable, documented, and consistent. Three things in practice.
Activity-based, not category-based. The calculation starts from what was bought, which product, from which supplier, in what quantity, not how much was spent.
A reproducible pipeline. Every invoice maps to a product or service, that maps to a sourced emission factor, and the calculation is preserved so it can be shown on request, not rebuilt from scratch.
Stable boundaries. Entities, categories, and methods stay consistent year over year, and any change is recorded with a reason, so a shift in the numbers reflects performance, not bookkeeping.
Bardo builds carbon data the way you would build any audited number: from source documents up. It reads enriched invoice and ERP data, ties each line to a specific supplier and activity, and applies a documented emission factor. Every figure in your report decomposes back to the transaction behind it. When the auditor asks where a number comes from, the answer is a record, not a category average.