Can we estimate Scope 3 and still pass assurance?

Yes. Estimates are expected in Scope 3 and are not a problem for assurance in themselves, because what fails is an undocumented estimate. The practitioner tests whether the method is appropriate and disclosed, the inputs are traceable, the application is consistent, and the estimation uncertainty is described honestly.

Our suppliers will not give us emissions data. What do we do?

You estimate, and you disclose that you estimated. Nothing in AASB S2 requires primary supplier data, because the standard works on information that is reasonable and supportable and available without undue cost or effort. Rank suppliers by estimated emissions, engage the top of that list, and leave the tail on a documented spend-based method.

What happens if we have to restate last year's emissions?

You restate the comparative and disclose what changed, why, and the effect. Restatement is expected as data improves and is not treated as a failure. What the assurance practitioner tests is whether you have a written policy setting out when you restate, and whether you applied it consistently.

Glossary›AASB S2 disclosure requirements / AASB S2 mechanics›Impracticable (AASB S2 relief)

Glossary term

Cluster C · C19

Tier 1 · differentiator

Impracticable (AASB S2 relief)

Definition

Impracticable is a defined term in AASB S2. Applying a requirement is impracticable when an entity cannot apply it after making every reasonable effort to do so. It is a much higher bar than undue cost or effort, and it applies only to specific requirements the standard names: correcting prior-period errors, revising comparative amounts, and estimating Scope 3 emissions.

AASB S2

· Appendix A defined term, applied at paragraph 83, Appendix B paragraph B57, Appendix D paragraphs B50 to B59 ·

In force

On this page

In practice
What the assurer does with it
Commonly confused with
Timing and relief
Sources
Related terms
Related questions

Cluster

C · AASB S2 disclosure requirements / AASB S2 mechanics, 25 terms

In practice

Two effort standards run through AASB S2 and conflating them is a real compliance risk in both directions. Undue cost or effort is a balanced cost-benefit judgement, used constantly, and it is genuinely proportionate. Impracticable means the entity cannot apply the requirement after making every reasonable effort. There is no cost-benefit weighing in that wording. Expense alone does not make something impracticable.

The bar is higher, and correspondingly the term appears in few places:

Where

Requirement

Effect of impracticability

Paragraph 83 (Appendix D)

Correct material prior period errors by restating comparative amounts

Restatement not required; Appendix D paragraph B56 requires disclosure of the nature of the error, the correction to the extent practicable, and if correction is impracticable, the circumstances and a description of how and from when the error has been corrected

Appendix D paragraph B59

Determining the effect of an error on all prior periods presented

Restate from the earliest date practicable

Appendix D paragraphs B50 to B53

Revise a comparative amount where a metric is redefined, replaced or newly introduced

The revised comparative need not be disclosed; Appendix D paragraph B54 requires the entity to disclose that fact

Appendix B paragraph B57

Estimate Scope 3 greenhouse gas emissions

The entity must instead disclose how it is managing its Scope 3 emissions

Appendix C paragraph C6

Adjust comparative information on first applying AASB S2025-1

Adjustment not required

Note the appendices. The comparatives and errors provisions are in Appendix D, the general requirements drawn from AASB S1. The Scope 3 provision is in Appendix B, the climate application guidance. Both appendices have a paragraph B57 and neither says the same thing.

Appendix B paragraph B57 deserves reading closely, because it is the one a private business is most likely to reach for and the one the standard most clearly discourages. It opens by stating that the Standard includes the presumption that Scope 3 emissions can be estimated reliably using secondary data and industry averages. Only “in those rare cases” where the entity determines estimation is impracticable does the relief engage, and even then the entity must disclose how it is managing its Scope 3 emissions. The presumption is doing the work. Because spend-based estimation using published industry averages is almost always available, an entity arguing that Scope 3 cannot be estimated at all is arguing against the standard’s own stated position. The honest route for an entity with poor Scope 3 data is estimation with disclosed uncertainty, not a claim of impracticability.

The practical drafting point is that impracticability is never a silent option. Every provision that permits it requires the entity to disclose that it applied it, and usually to explain the circumstances. A relief that must be announced is a relief the assurer will test.

What the assurer does with it

Because the claim is that something could not be done after every reasonable effort, the assurer tests the effort, and the evidential burden sits with the entity. They ask what was attempted, when, by whom, and what the outcome was. A claim with no record of attempts fails immediately, because the definition is about effort expended.

For a comparatives or error claim they ask what source data exists for the prior period, whether it was requested, and what the response was: a documented supplier or system enquiry with a dated negative answer supports the claim; an assumption that the data would not be available does not. For a Scope 3 claim under Appendix B paragraph B57 they start from the presumption in the standard and ask why secondary data and industry averages could not be used, which is a question most entities cannot answer, and they then test whether the required disclosure about how Scope 3 is being managed was actually made.

They accept a claim supported by a dated record of specific attempts, a clear statement of what stopped them, and the disclosure the relevant paragraph requires. They reject impracticability asserted on grounds of cost, asserted over data the entity holds or could obtain from its own systems, asserted without the accompanying disclosure, and repeated in a later period with no evidence of any fresh attempt. A claim carried forward unchanged for a second year is the reliable trigger for a deeper look, because the standard’s threshold is about what the entity cannot do now, not what it could not do last year.

Commonly confused with

Reasonable and supportable information without undue cost or effort, which is the general proportionality standard and is far more permissive. That distinction is the whole value of this entry: an entity may routinely make undue-cost-or-effort judgements, and should almost never be claiming impracticability. Also confused with the Appendix C transitional reliefs, which are automatic first-year entitlements requiring no argument at all. If a transitional relief covers the situation, use it and do not construct an impracticability case.

Timing and relief

Not time-limited. The term is a permanent feature of the standard, tested against the entity’s circumstances in each reporting period. Because it turns on what the entity cannot do after every reasonable effort, a position must be re-established each year rather than carried forward.