ISSA 5000 arrives on 15 December 2026
The global standard for assuring sustainability information. It does not change what you report – it changes how hard it is to prove, and that lands on your evidence rather than your arithmetic.
Engagements for periods beginning on or after 15 December 2026
Applies to assurance engagements on sustainability information for periods beginning on or after this date. Early application is permitted.
Limited and reasonable assurance are both covered, with the requirements for each clearly differentiated.
Framework neutral by design. CSRD and ESRS, ISSB, GRI or voluntary reporting are all in scope of the standard.
The gap is evidence, not arithmetic
ISSA 5000 requires the practitioner to identify and assess risks of material misstatement, and then design procedures that respond to those risks. Under limited assurance that assessment happens at the disclosure level. Under reasonable assurance it happens at the assertion level for each disclosure, which means more testing and more evidence.
What that means for the company being assured is straightforward. The provider is not checking whether your total adds up. They are asking where each component came from, which version of which emission factor was applied, who approved a change and when, whether an estimate was labelled as one, and whether last year can be reproduced on last year’s methodology.
What providers typically find
- Figures assembled in spreadsheets, offline, with no record of the workings
- Emission factor sources and versions undocumented
- No log of who changed a value, or why
- Estimates presented as measurements
- Prior periods that cannot be reproduced after a factor update
- The same person preparing and approving the number
What they should find
- Every figure traceable to a source document
- Factor source and version stored on the number itself
- An immutable change log with user and timestamp
- Estimates labelled, with the basis shown
- Prior periods reproducible on the original methodology
- Enforced separation between preparer and approver
The cost and difficulty of an engagement is driven less by the complexity of the numbers than by how much of the fieldwork is spent reconstructing evidence that should already have existed.
Where the platform stands today
Available now. Datapoint-level lineage back to source documents, an immutable change log with user and timestamp, enforced segregation between preparer and approver, factor source and version stored on each calculation, and prior periods reproducible on the methodology that applied at the time. These are the controls an assurance provider tests, and they are in the product today.
In development. We are building ISSA 5000-specific tooling on top of that foundation: a mapping from each disclosure to the evidence supporting it, a readiness view that shows which disclosures would survive testing and which would not, and an export pack designed for the way practitioners work through an engagement. This is being built now and is not yet released.
If ISSA 5000 is on your horizon, a demo is the honest way to see what exists today and what is still on the way. See how the audit trail works.
Questions
What is ISSA 5000?
ISSA 5000, General Requirements for Sustainability Assurance Engagements, is the IAASB’s global standard for assuring sustainability information. It is framework neutral, so it applies whether you report under CSRD and ESRS, ISSB, GRI or a voluntary framework, and it can be used by both accounting and non-accounting assurance providers.
When does ISSA 5000 apply?
It applies to assurance engagements on sustainability information reported for periods beginning on or after 15 December 2026, or reported as at a specific date on or after 15 December 2026. Early application is permitted, so some engagements will run under it sooner.
What is the difference between limited and reasonable assurance under ISSA 5000?
ISSA 5000 covers both. Under limited assurance the practitioner identifies and assesses risks of material misstatement at the disclosure level. Under reasonable assurance they do so at the assertion level for each disclosure, which requires more evidence and more testing of controls. Most first engagements are limited assurance.
Does ISSA 5000 apply to my company if I am not in CSRD scope?
ISSA 5000 governs the assurance engagement rather than the obligation to report, so it applies whenever sustainability information is being assured, including voluntary assurance. If a customer, lender or investor asks for assured figures, the engagement will be run to this standard.
What does ISSA 5000 change in practice?
The numbers matter less than the evidence behind them. Practitioners test the chain from a published figure back to its source, the controls over who changed what and when, whether estimates are labelled as estimates, and whether a prior period can be reproduced on the methodology that applied at the time.
See the evidence chain on real data
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