Glossary›Assurance, audit evidence and working papers›Source document (emissions evidence)
Glossary term
Cluster A · A14
Tier 1 · differentiator
Source document (emissions evidence)
Definition
A source document is the original record that first captured an activity: a fuel invoice, an electricity bill, a meter reading, a fleet card statement, a freight manifest, a lease. It is created by or received from an outside party at the time of the transaction, which is why assurers treat it as the strongest evidence available.
On this page
In practice
The defining characteristics are external origin and contemporaneity. A supplier invoice qualifies. A summary of supplier invoices prepared by your team six months later does not, though it may be a useful working paper referencing documents that do.
The practical failure is retention. Emissions data is collected across a full financial year and the supporting documents are often held by whoever received them: a site manager’s email, a procurement portal, a supplier login that expires. Assurance happens after year end, and by then some source documents are gone. Collecting them monthly during the year, into one place, is the cheapest thing a first-time reporter can do.
What the assurer does with it
The assurer selects items, requests the source document, and agrees the quantity, the period and the entity named on it. They reject documents that name a different legal entity to the one reporting, cover a period straddling the year end with no apportionment, are screenshots without identifying detail, or have been re-keyed rather than provided. They also test the other direction: given a population of source documents, are all of them in the inventory. Missing documents are more damaging than wrong ones, because a missing document is a completeness failure and completeness cannot be fixed by explanation.
Commonly confused with
Supporting documentation generally. A calculation memo supports a figure but is not a source document; it is a working paper that should reference source documents.
Sources
1
ASSA 5000 General Requirements for Sustainability Assurance Engagements
AUASB
2
Review status
Review required
Last reviewed
15 September 2026
Editorial pass, unsigned
Reviewer required
Registered company auditor
Next scheduled review
1 July 2027
Part of
Cluster A, Assurance, audit evidence and working papers
47 terms on what an assurance provider tests, what they accept as evidence, and what a preparer has to be able to produce.
Related terms
Where source documents sit in the evidence hierarchy
The procedure that calls for these documents
The quantity extracted from the source document
Related questions
What evidence do we need for each emissions number?
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Every reported number needs a source document you did not create for the report, the activity data drawn from it, the emission factor and its published edition, and the calculation joining them. Fleet fuel needs litres from fuel card statements, electricity needs kWh by site from retailer invoices with the matching state factor, and refrigerants need kilograms by gas type from service records.
What will our auditor actually ask for?
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In year one they ask for evidence behind the disclosures that are actually assured: Scope 1 and Scope 2 emissions, your governance disclosures, and the specified strategy paragraphs on climate risks and opportunities. In practice that means source documents, a calculation they can rebuild from those documents, and minutes showing the governance you described actually happened.
Can we use spreadsheets, or will the auditor reject them?
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Spreadsheets are acceptable and no Australian standard requires software. What gets rejected is an unauditable spreadsheet: hard-coded numbers with no source, broken formula chains, no version control and no record of who changed what. A disciplined spreadsheet passes assurance and an undisciplined system does not.
Other terms in this cluster
Source document (emissions evidence)