Who Can Verify My CSRD Report?

Introduction

Under the Corporate Sustainability Reporting Directive (CSRD), all sustainability reports will need to be verified — or, in EU terms, assured — by an independent professional. This verification confirms that your data is consistent, traceable, and free from material misstatements.

But who exactly is allowed to do it? And do small and growing businesses (SMEs) need to work with the same auditors as large listed companies?

This article breaks down who can verify your CSRD report, the difference between statutory and independent assurance providers, and what’s expected for small and growing businesses (SMEs) and VSME reporters.

For background on whether your company needs assurance at all, read Does CSRD Reporting Need to Be Audited for SMEs?.

1. The Legal Framework for CSRD Verification

The CSRD Directive (EU 2022/2464) requires all companies under its scope to have their sustainability information subject to assurance — meaning an independent check that the report is credible and complete.

Initially, this will be at the limited assurance level (moderate scrutiny), with a transition to reasonable assurance (similar to financial audit) expected around 2028–2030.

The assurance process must follow recognised international standards such as ISAE 3000 (Revised) or EU-level assurance standards once adopted.

2. Who Can Provide CSRD Assurance

Each EU Member State must allow assurance to be performed by one of the following:

A. Statutory Auditors or Audit Firms

These are your registered financial auditors, already authorised under the EU Audit Directive. They can:

• Perform both financial and sustainability assurance.
• Combine the two audits for efficiency.
• Provide limited or reasonable assurance depending on your reporting stage.

Most large or listed SMEs will use their existing audit firm for CSRD assurance.

B. Independent Sustainability Assurance Providers

These are specialised firms or professionals accredited by a national authority to conduct non-financial assurance. They often have expertise in:

• Sustainability data, ESG frameworks, and GHG accounting.
• Sector-specific impacts (e.g. energy, manufacturing, services).

For voluntary or VSME reporting, independent providers are often a better fit because they offer flexible scopes and lower costs while still meeting CSRD’s independence and quality criteria.

3. Assurance Rules for SMEs and VSME Reporters

Not all SMEs need verification immediately — the rules depend on whether your company falls under mandatory or voluntary reporting.

If you are reporting voluntarily under the VSME Standard, you can decide:

• Whether to have your report externally verified.
• Which parts to include (e.g. GHG data only, or the full report).

Even without formal verification, it’s smart to use assurance-ready methods — clear documentation, defined data owners, and transparent estimation approaches.

For guidance on assurance readiness, see How to Prepare for Your First CSRD Audit or Review.

4. What Verification Actually Involves

During CSRD verification, your assurance provider will:

1. Review your data collection processes and controls.
2. Check that your disclosures match the ESRS requirements.
3. Assess traceability — can each figure be linked to its source?
4. Verify that methods, assumptions, and emission factors are reasonable.

They won’t expect perfection but will check that your approach is logical, documented, and consistently applied.

Under limited assurance, the objective is to provide moderate confidence that no material misstatements exist — not to recalculate every data point.

5. How to Choose the Right Assurance Provider

When selecting a verifier, consider:

• Accreditation: Are they licensed under national law or recognised by a professional body?
• Experience: Do they understand CSRD, ESRS, and the VSME framework?
• Sector knowledge: Have they worked with companies in your industry?
• Scope flexibility: Can they focus on specific areas (e.g. GHG data, social disclosures)?
• Independence: They must not be involved in preparing your report.

For SMEs, working with smaller ESG consultancies or specialised assurance firms can be more cost-effective while maintaining compliance.

6. What Happens After Verification

After completing assurance, your provider issues an Assurance Report, summarising:

• The level of assurance (limited or reasonable).
• The standards used (ISAE 3000, national standards).
• The scope of work (which disclosures were verified).
• Their conclusion — often phrased as:

  “Based on our review, nothing has come to our attention that causes us to believe that the sustainability information is materially misstated.”

This report is published alongside your CSRD disclosure, increasing credibility and stakeholder trust.

Frequently Asked Questions

Can I choose someone other than my financial auditor?

Yes, if national rules allow. Many SMEs choose independent ESG assurance providers for flexibility and expertise.

Is assurance required for voluntary VSME reports?

No, it’s optional. But third-party verification can strengthen your reputation with banks and clients.

Will all EU countries follow the same rules?

They’ll follow the same EU framework, but each Member State will decide how to accredit and supervise assurance providers.

How do I know if a provider is accredited?

Check your national authority’s register (e.g. Chamber of Auditors or sustainability assurance registry).

Key Terms

• Assurance – Independent verification that reported information is accurate and reliable.
• Limited assurance – Moderate-level review focused on plausibility and consistency.
• Reasonable assurance – High-level verification, similar to a financial audit.
• ISAE 3000 (Revised) – International assurance standard for non-financial data.
• VSME Standard – Voluntary EU sustainability reporting framework for SMEs.

Conclusion

Only accredited professionals — either statutory auditors or independent assurance providers — can verify CSRD reports. For most SMEs, external assurance will start with limited assurance, focusing on reasonableness rather than absolute precision.

Even if your report isn’t mandatory or audited yet, choosing an assurance-ready approach will help you build trust with clients, investors, and regulators — and make future verification seamless.

To understand how assurance fits into your reporting timeline, consult our annual CSRD reporting calendar.