Assurance of sustainability information is required in the EU for companies within CSRD scope, at a limited assurance level. The February 2026 Omnibus directive removed the plan to move to reasonable assurance, pushed the deadline for EU limited assurance standards to 1 July 2027 and narrowed the number of companies in scope. Member States can let auditors other than the financial statement auditor, or accredited independent providers, give the opinion.
What EU assurance covers
Under the CSRD, the statutory auditor gives an opinion, based on a limited assurance engagement, on whether sustainability reporting complies with EU requirements, including the reporting standards, the process to identify reported information, digital mark-up and the EU Taxonomy disclosures. Member States may let a different statutory auditor or an accredited independent assurance services provider give the opinion. Reports of non-EU groups published under Article 40a are accompanied by an assurance opinion from a person authorised in the third country or a Member State.1234
What changed in 2026
Directive (EU) 2026/470 removed the requirement for reasonable assurance standards and gave the Commission until 1 July 2027 to adopt limited assurance standards. Because the reporting scope now starts at EUR 450 million turnover and 1,000 employees, far fewer companies need assurance at all.567
| Point | Rule | Source |
|---|---|---|
| Level | Limited assurance; reasonable assurance standards requirement removed | Directive (EU) 2022/2464 recital 60; Directive (EU) 2026/470 |
| Provider | Statutory auditor; Member State may allow another auditor or accredited provider | Directive (EU) 2022/2464 recital 61 |
| EU standard | Commission to adopt limited assurance standards by 1 July 2027 | Directive (EU) 2026/470 |
| Scope | Over EUR 450 million turnover and 1,000 employees | Directive (EU) 2026/470 |
Decisions to make
- Is the entity still in CSRD scope after the 2026 thresholds?7Assurance follows reporting; companies below the thresholds have no EU assurance duty.
- Will the financial statement auditor also provide sustainability assurance?3Member States may allow other auditors or accredited providers, which changes tendering options.
- Which assurance standard will the provider apply until the EU standard is adopted?6The EU limited assurance standard is not due until 1 July 2027.
Documents usually needed
- Sustainability report and digital mark-up file
- Double materiality assessment and process documentation
- EU Taxonomy disclosure workings
- Assurance engagement letter specifying limited assurance and the standard applied
- Data lineage and controls documentation for reported metrics
Common mistakes
- Budgeting for reasonable assurance that EU law no longer plans to require
- Assuming only the financial statement auditor can give the opinion without checking national law
- Leaving Taxonomy disclosures out of the assurance scope
- Preparing for assurance on the pre-2026 scope
Questions businesses ask
Will CSRD assurance move to reasonable assurance?
Not under current EU law. The 2026 amendments removed the requirement to adopt reasonable assurance standards.5
Can a non-audit firm provide CSRD assurance?
Only where the Member State allows accredited independent assurance services providers.3
What this guide does not yet confirm
These points need checking with a qualified local professional before you rely on them.
- The operative text of Article 34 of Directive 2013/34/EU and of the Audit Directive provisions on sustainability assurance could not yet be checked in full; recitals were used.
- IAASB ISSA 5000 and its effective date could not yet be checked.
- National choices in Germany and France on assurance providers were not checked.
- Assurance of UK SRS, ISSB-based or Singapore climate disclosures was not researched.
Sources and review status
Each statement is numbered to the source it was checked against. We use official sources where we can, and each statement says whether it was checked against an official or a secondary source. Sources last checked on 19 October 2026. None of it has been professionally reviewed yet: it is research checked against official and secondary sources by WONE Global, not legal or tax advice.
Under the CSRD the statutory auditor gives an opinion on the compliance of sustainability reporting with Union requirements based on a limited assurance engagement, covering the reporting standards, the process to identify reported information and the digital mark-up requirement. EU undertakings in CSRD scope; recital 60 explains the operative provisions in Article 34 of Directive 2013/34/EU, which could not yet be checked in full.
The CSRD assurance provider should also assess whether the undertaking's reporting complies with the EU Taxonomy disclosure requirements in Article 8 of Regulation (EU) 2020/852. EU undertakings in CSRD scope.
EU Member States may allow the sustainability assurance opinion to be given by a statutory auditor other than the one auditing the financial statements, or by an accredited independent assurance services provider. Member State option; independent assurance services providers are bodies accredited under Regulation (EC) No 765/2008. National choices were not checked.
Sustainability reports of third-country undertakings published in the EU are to be accompanied by an assurance opinion from a person or firm authorised under the national law of the third-country undertaking or of a Member State. Article 40a reports by EU subsidiaries or branches of non-EU groups; thresholds raised by Directive (EU) 2026/470.
The 2026 Omnibus amendments remove the requirement for the Commission to adopt reasonable assurance standards, so sustainability assurance under EU law stays at limited assurance. EU; Directive (EU) 2026/470 of 24 February 2026.
The 2026 Omnibus amendments move the deadline for the Commission to adopt limited assurance standards for sustainability reporting from 1 October 2026 to no later than 1 July 2027. Until EU standards are adopted, national assurance standards apply.
After the 2026 amendments, EU sustainability reporting, and therefore its assurance, applies only to undertakings exceeding both EUR 450 million net turnover and an average of 1,000 employees. Directive 2013/34/EU as amended; national transposition to be checked.
Questions on this topic
7 statements on sustainability assurance
