The demands on sustainability reporting are increasing, and with them the importance of the CSRD audit for companies in Germany and throughout Europe. With the Corporate Sustainability Reporting Directive (CSRD) , the European Union is creating a new standard for transparency and comparability. The goal is to systematically and comprehensibly integrate environmental, social and governance issues (ESG) into corporate reporting.
1. Why the CSRD audit is now in focus
Even though the final elaboration of the CSRD following the Omnibus Proposal at the European level is still ongoing and its legal implementation in Germany has not yet been completed, it is clear: The CSRD audit will become mandatory for many companies and for others a strategic lever to position themselves for the future. The CSRD directive not only requires meaningful sustainability reporting but also its external verification based on the principle of limited assurance (Limited Assurance). This means: companies must set up processes, data, and responsibilities in a way that meets the growing requirements.
The view of the current legal situation is particularly relevant here. Until the full implementation of the CSRD, the CSR Directive Implementation Act (CSR-RUG) continues to apply in Germany. However, adjustments and transitional arrangements are already emerging, for example through the “Stop the clock” proposal and planned changes to the scope at EU level.
Companies that adopt structured sustainability reporting early on gain clear advantages: They not only comply with regulatory requirements but also strengthen their position with investors, customers, and business partners.
2. The regulatory framework: The basis of every CSRD audit
Anyone who wants to pass the CSRD audit successfully must know the legal framework exactly. The Corporate Sustainability Reporting Directive (CSRD) is the new European directive that obliges companies to provide comprehensive and standardized sustainability reporting. It gradually replaces the previous regulations of the Non-Financial Reporting Directive (NFRD) and, in Germany, the CSR Directive Implementation Act (CSR-RUG).
Currently, the legal framework of the CSR-RUG still applies in Germany. This means: companies that have previously been required to report non-financial information are still obliged to report (pursuant to §§ 289b et seq. or 315b et seq. HGB). Only with the full implementation of the CSRD will this framework be replaced. This transition phase requires particularly careful planning, as many requirements apply in parallel or overlap in time.
Voluntary Reporting as a Strategic Advantage
Not all companies are directly subject to reporting requirements. Nevertheless, it can be strategically advantageous to start structured sustainability reporting early. A possible framework for this is the Voluntary Reporting Standard for SME (VSME) , which the European Commission has recommended as a voluntary reporting standard. This particularly facilitates small and medium-sized enterprises’ entry into reporting and thus also their preparation for a later CSRD audit.
The voluntary reporting standard is not subject to mandatory external auditing. Nevertheless, it can be advantageous to obtain external validation of the information. Be it for the use of certain environmental claims towards consumers (see EmpCo Directive) or for a better rating certificate (e.g., EcoVadis).
Looking to the Future: ESRS and European Audit Standards
The CSRD refers to the European Sustainability Reporting Standards (ESRS) , which set uniform requirements across Europe. These standards are being revised at the time of writing this article, including through the so-called Quick Fix Delegated Act, which extends and simplifies transitional provisions.
New European auditing standards are currently emerging – particularly ISSA 5000 – which will be decisive for the external audit of sustainability information in the future. Companies that actively follow these developments gain a clear advantage in implementation and in preparing for their CSRD audit.
3. Obligations and scope of the audit according to CSRD
The CSRD audit is not only a formal control, it is based on clearly defined obligations and standards that companies must meet. At the center is the mandatory sustainability reporting, which in the future will be as binding and audit-relevant as the classic financial report. For many companies, this means: new processes, new data requirements and a significantly higher degree of transparency.
Which Standards Apply?
Reporting is based on the European Sustainability Reporting Standards (ESRS). They form the central set of rules for the content, structure and methodology of sustainability reporting.
Key requirements include:
a double Materiality Assessment (Impact and Financial Materiality)
disclosure requirements on environmental, social and governance aspects (ESG)
sector-specific reporting requirements (will be added gradually)
specification of methods, data sources and assessment bases used
The Quick Fix Delegated Act extends transitional arrangements and makes it easier for companies to get started in the initial phase.
External Audit Becomes Mandatory
A central difference to previous regulations: Sustainability reports will be subject to mandatory external audit in the future. This means that auditors or other approved auditors will check the information according to defined standards.
The audit obligation begins:
from 2024 for large capital market-oriented companies with more than 500 employees,
from 2025–2028 for other groups, staggered by company size (see CSRD development),
In addition, there is the option of voluntary audits for non-obligated companies.
For the audit of the sustainability report, the auditing standard with limited assurance (Limited Assurance) is provided.
4. Preparation for the CSRD audit in practice
The CSRD audit presents many companies with a new challenge. It requires not only the existence of a sustainability report, but also a resilient, comprehensible and auditable information base. Those who create clear structures at an early stage reduce risks, save time and ensure a smoother audit process.
Create Clear Processes and Responsibilities
A central success factor is a clearly structured internal process. Sustainability reporting must not be a by-product, but must be understood as an integral part of corporate management. This includes:
Definition of responsibilities: Who is responsible for which topics, data and key figures?
Involvement of all relevant areas: Sustainability concerns not only ESG teams, but also finance, controlling, human resources, purchasing, production and communication.
Integration into existing reporting structures: With the help of structured Green Controlling, sustainability data can be collected and audited more efficiently.
A well-structured process not only facilitates the reporting itself, but makes the CSRD audit more predictable for companies.
Data Quality and Documentation as a Basis
Auditors require complete and verifiable documentation of all relevant information. Companies should therefore, at an early stage:
systematically record data sources and responsibilities,
establish plausibility and consistency checks,
clearly document interpretation decisions regarding the ESRS,
clearly define external data suppliers and stakeholders.
Information from the value chain is particularly critical, as it is often not fully controllable internally. A transparent approach helps here, for example through coordinated processes with suppliers and partners.
Strategically Design Time Planning
A realistic and early time planning is helpful for a successful CSRD implementation, including auditing. It should include several phases:
Materiality Assessment and strategy development
Data collection and internal coordination
Report preparation and quality assurance
Audit preparation and feedback loops
Finalization of the sustainability report
Since many processes are new, companies should plan buffer times, especially for the first audit. Early coordination with the auditors helps to clarify open questions in good time and avoid unnecessary delays.
Establishment of an Internal Control System
In order to make sustainability reporting permanently auditable, the establishment of an internal control system (ICS) is decisive. This system ensures that data is collected and processed consistently, correctly and comprehensibly. It includes:
Process descriptions and control documentation,
technical systems for data collection,
clear release processes and responsibilities,
regular internal audit mechanisms.
The ICS is not a “nice to have”, it becomes the decisive proof of quality for the CSRD audit. Typically, controlling is responsible for such a control system.
Use External Expertise
Not all companies have the necessary resources or expertise to implement the complex requirements of the CSRD audit on their own. Therefore, it can be beneficial to involve external experts or CSRD consultants.
In this way, a regulatory obligation becomes an opportunity to strategically and professionally anchor sustainability in the company.
5. Types of audits and requirements for the CSRD audit
The CSRD audit ensures that the published ESG data is credible, reliable and comparable. The audit process is based on established audit standards from financial reporting with some special features.
Limited vs. Reasonable Assurance
The CSRD audit requires limited assurance (Limited Assurance). This means that auditors assess the plausibility and appropriateness of the reported information, but with a smaller scope of audit than for a financial statement audit. Typically, the audit procedures include:
Surveys and interviews with responsible persons,
Analysis of processes and controls,
Sample checks of individual information,
Assessment of the Materiality Assessment and the underlying methods.
An audit with reasonable assurance (Reasonable Assurance) was originally planned, but is currently no longer foreseen for the CSRD report. This standard is more akin to a classic financial audit in its depth and includes, among other things:
More extensive tests and samples,
Verification of the effectiveness of internal controls,
Detailed validation of key figures, data sources and methods.
Audit Standards: ISSA 5000 and ISAE 3000
The external audit of sustainability reporting is based on international standards. The following are particularly relevant:
ISAE 3000 (Revised): current standard for audits of non-financial information, which will be applied until the full introduction of the ISSA standards.
ISSA 5000 : the future European auditing standard specifically for sustainability information, developed by the International Auditing and Assurance Standards Board (IAASB).
These standards regulate, among other things:
the structure and methodology of the audit,
the requirements for audit evidence,
the formulation of the audit opinions,
and the quality assurance of the audit process.
Audit Opinions and Their Significance
At the end of the CSRD audit, there is an audit opinion that provides information about the reliability of the reporting. In general, a so-called negatively worded audit opinion is issued with limited assurance, for example:
“On the basis of the audit procedures performed and the audit evidence obtained, nothing has come to our attention that causes us to believe that the consolidated sustainability statement is not presented fairly, in all material respects, in accordance with applicable requirements.”
In an audit with reasonable assurance, the opinion is positively formulated, similar to an audit opinion in financial auditing. Companies can also choose a combination of both audit types, for example, if particularly sensitive topics are to be examined in more detail (e.g., climate targets or supply chain information).
Practical Implications for Companies
The chosen type of audit directly influences:
the time and organizational effort,
the depth of internal documentation,
the required resources,
and the level of reputation with stakeholders.
6. Strategic implications of the CSRD audit
The CSRD audits is far more than an additional legal requirement. If understood correctly, it can become a strategic instrument for corporate sustainability. This is because the transparency and structure that are created in the course of sustainability reporting have an impact far beyond regulatory obligations, on financing, market positioning, competitiveness and reputation.
ESG Transparency as a Competitive Advantage
Customers, investors, and business partners today expect more than just financial figures. Companies that disclose their sustainability strategy and have it externally audited actively strengthen trust in their business practices.
The CSRD audit provides additional credibility because the published information is not only created internally, but is also externally verified. That can:
Facilitate access to capital, as banks and investors are increasingly incorporating ESG criteria into their decisions,
Strengthen supply chain relationships by transparently and verifiably meeting sustainability requirements,
Increase brand image and employer attractiveness, especially among young talents who value sustainability.
Sustainability Reporting as a Management Tool
The requirements of the CSRD mean that sustainability information is being integrated into corporate management. Companies that systematically collect and use their ESG data can:
Identify and manage risks early on (e.g. climate risks, supply chain risks),
Identify opportunities (e.g. efficiency gains, innovation potential),
Measurably link sustainability goals with the business strategy.
This makes the CSRD audit a driver for professionalization and strategic development, and not just a pure compliance exercise.
Signaling Effect for Stakeholders
Audited sustainability reporting sends a strong signal: “We take sustainability seriously and allow ourselves to be measured against it.”
This creates trust with:
Investors who are increasingly demanding binding ESG data,
Customers who expect sustainable supply chains,
Employees who value responsible action,
Regulatory authorities that check traceability and transparency.
In particular, companies that start early with high-quality reporting gain a first-mover advantage and position themselves as a reliable partner in the transformation.
Connection to further Sustainability Requirements
The CSRD does not stand in isolation. It is part of a larger regulatory framework that gradually strengthens the anchoring of sustainability. This includes, in particular, the EU Taxonomy Regulation and the Corporate Sustainability Due Diligence Directive (CSDDD).
Good preparation for the CSRD audit therefore also means leveraging synergies and setting up reporting and control processes in such a way that they meet several regulations at the same time.
7. Recommendations for action & checklist for preparing for the CSRD audit
Good preparation is the key to a successful CSRD audit. The following checklist helps companies to systematically build up their internal processes, create transparency and minimize audit risks.
1. Set the strategic course
Clearly define responsibilities for sustainability reporting
Integrate sustainability strategy with corporate strategy
Actively involve management and supervisory bodies in the process
Take into account the potential impact of other regulations (e.g. EU taxonomy, CSDDD)
2. Review scope and reporting obligations
Determine whether and from when the company is subject to reporting requirements
Check transitional periods and possible exemption regulations
Decide whether to report voluntarily early (first-mover advantage)
Involve key suppliers and partners in the process (value chain)
3. Set up data management and documentation
Identify and centrally record relevant ESG data sources
Establish plausibility and quality checks
Document questions of interpretation regarding the ESRS
Define processes for data collection along the value chain
Ensure comprehensible documentation for auditors
4. Implement internal control system (ICS)
Standardize processes for data collection and processing
Define and document control and release processes
Clearly define roles and responsibilities in the ICS
Plan regular internal audits and improvement cycles
5. Design the schedule realistically
Set up a multi-stage project plan with clear deadlines
Plan feedback loops and coordination with auditors
Schedule report preparation and review early
Incorporate buffer times — especially during the first CSRD audit
6. Communication and training
Create internal awareness and involve all relevant departments
Conduct CSRD training and courses on ESRS, reporting processes, and audit requirements
Clearly structure stakeholder communication (internal and external)
Communicate results transparently and understandably
7. Use external support in a targeted manner
Contact auditors early
Involve external specialist advice where internal know-how is lacking
Analyze best practices from other industries
Evaluate ESG software solutions and supporting technologies
8. Outlook & further resources
The CSRD audit will continue to gain importance in the coming years and become an integral part of corporate governance.
Companies that create solid structures now will benefit twice over: from more efficient processes and a clear advance of trust in the market. Companies should pay particular attention to the following developments:
New ESRS versions and sector-specific standards > Subscribe to the free ‘CSRD Compass’ Newsletter to not miss updates!
Integration with other EU regulations (e.g., Taxonomy, CSDDD)
Digitalization of reporting through standardized data formats and platforms
