CSRD audit preparation raises a lot of practical questions. In this FAQ, we address the most common questions sustainability and finance teams ask about preparing for limited assurance under the Corporate Sustainability Reporting Directive.

What is limited assurance under CSRD?

Limited assurance is the standard of third-party review required for CSRD sustainability statements. Under limited assurance, an accredited auditor performs procedures sufficient to identify material misstatements, but does not provide the higher level of scrutiny associated with reasonable assurance (the standard for financial statements).

In practice, limited assurance requires that your sustainability disclosures are traceable, consistent, and based on documented methodologies. The auditor will review key metrics, check for internal consistency, and assess whether your double materiality assessment is defensible.

Who can provide CSRD assurance?

Under CSRD, assurance must be provided by an accredited assurance provider. In most EU member states, this means a registered statutory auditor or audit firm. In the Netherlands, Standard 3810N governs the assurance engagement until the EU-wide European Standard on Sustainability Assurance (ESSA) is adopted.

What does an auditor actually review?

A CSRD auditor will typically review:

• Your double materiality assessment and the rationale for materiality decisions
• The data collection process and internal controls for sustainability data
• Key quantitative metrics (emissions, workforce data, etc.) and their supporting evidence
• Consistency between the sustainability statement and financial reporting
• Completeness of disclosures relative to your DMA conclusions

What evidence do I need to prepare?

For each quantitative metric in your sustainability statement, you should be able to provide:

• The source document or data system the figure came from
• The calculation methodology applied
• The emission factor or conversion factor used (if applicable)
• Who collected and verified the data
• Any material assumptions or limitations

How do I make my double materiality assessment audit-ready?

Your DMA documentation should include:

• A description of the process followed (who was involved, what sources were consulted)
• How stakeholders were engaged
• The scoring rationale for each sustainability topic
• The conclusions reached and which topics are material
• Why certain topics were assessed as not material

Auditors will look for evidence that the DMA was a genuine, structured process — not a checkbox exercise.

What are the most common CSRD audit failures?

Common reasons companies struggle with limited assurance:

• No traceable audit trail from disclosure to source data
• Inconsistencies between sustainability and financial reporting
• Poorly documented or indefensible DMA
• Scope 3 emissions with no supporting methodology documentation
• Data collected in spreadsheets with no version control

How should I engage my auditor during preparation?

Engage your assurance provider early — before your data collection is complete, not after. Early engagement helps you understand what evidence they will require, align on methodology questions before they become audit findings, and build confidence that your process will meet their requirements.

How does Coolset support audit readiness?

Coolset is designed for CSRD audit readiness from the ground up. Every data point entered into the platform is linked to its source, every calculation has a documented methodology, and the full audit trail is exportable for your assurance provider. The platform also generates XBRL output for machine-readable filing. Book a demo to see how it works.