CSRD assurance should influence the sustainability reporting process from the beginning. Limited assurance is not a final check applied to a finished ESRS report; it is an evidence-based engagement over how the sustainability information was prepared and presented.
The EU assurance framework was still evolving in 2026. Companies need to follow the rules transposed in the relevant Member State while preparing for a harmonized EU standard based on ISSA 5000.
What is required and what is still developing
CSRD requires sustainability statements to receive limited assurance. The exact provider, oversight, and national implementation depend on applicable law.
Until a harmonized standard is adopted, the CEAOB’s 2024 non-binding guidelines provide a common European approach where no national standard governs. The European Commission has requested technical advice for an EU limited assurance standard based on ISSA 5000, with clearly identified EU additions and carve-outs.
As of August 10, 2026, the Commission had requested that advice by September 30. Reporting teams should monitor the final delegated act and national regulator guidance rather than assuming the international standard alone satisfies CSRD.
Limited assurance still requires robust evidence
Limited assurance involves less assurance risk reduction than reasonable assurance and usually different procedures, but it is not light-touch validation. Practitioners need sufficient appropriate evidence to support their conclusion.
For an ESRS sustainability statement, that can include:
- The double materiality assessment and its governance.
- Compliance with ESRS reporting requirements.
- Processes used to identify reported sustainability information.
- Quantitative metrics, estimates, and forward-looking disclosures.
- Value-chain information and permitted estimation approaches.
- Digital tagging and consistency with other published information, as applicable.
The final EU standard will determine the precise engagement requirements. The company’s no-regret task is to make every material disclosure traceable and reviewable.
Build an assurance matrix
Map each disclosure in the sustainability statement to the applicable ESRS paragraph, materiality decision, source, method, control, owner, evidence, and report location.
Classify evidence by type:
- Criteria evidence: policies, definitions, reporting boundaries, and methodology decisions.
- Source evidence: system exports, invoices, contracts, surveys, and operating records.
- Calculation evidence: models, factors, conversions, estimates, and change history.
- Control evidence: preparer and reviewer sign-offs, reconciliations, exceptions, and approvals.
- Narrative evidence: minutes, risk registers, transition plans, scenario models, and target governance.
Evidence should show context, period, source, preparer, and version. A screenshot without those attributes can be difficult to authenticate or reproduce.
Treat double materiality as an assured process
Preserve the full universe of impacts, risks, and opportunities considered—not only the final list. Retain stakeholder inputs, scoring criteria, thresholds, challenge sessions, changes, and board approval.
The IAASB’s 2026 materiality FAQ confirms that ISSA 5000 can address double materiality where the reporting criteria require it. That supports interoperability, but the final EU standard may impose additional CSRD-specific expectations.
Run a dry close
Before year-end, select one disclosure from each material topic and test backward and forward tracing. Include a narrative claim, a manual estimate, a Scope 3 category, and a value-chain datapoint.
Log gaps by root cause and remediate the process. Common failures include incomplete entity populations, uncontrolled spreadsheets, missing review evidence, inconsistent definitions, and disclosures copied between reports after the assured version was frozen.
Agree with the provider on scope, assurance level, component work, use of experts, evidence access, timetable, and change control. Keep readiness consulting separate from the independent conclusion where independence rules require it.
Carbon Impact’s CSRD reporting solution and ISSA 5000 assurance-readiness workflow connect ESRS requirements to controlled evidence and review.
This article reflects information available on August 10, 2026. EU and national assurance requirements may change. This is general information, not legal or assurance advice.
Sources
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