The transposition of the CSRD in Dutch legislation was delayed at the end of 2024, and parliamentary discussion of the proposals during 2025 was further postponed pending the outcomes of the Omnibus proposals (Social Economic Council 2025; Tweede Kamer der Staten-Generaal 2025b). At the end of December 2025, Parliament was requested to take into account the final Omnibus conclusions when discussing the Dutch implementation proposals (Ministerie van Financiën 2025). This means that, at the time of the research Dutch legislation still reflected the NFRD and did not yet include CSRD reporting and assurance requirements. With respect to the CSRD member state option regarding the type of assurance provider, the Dutch government expressed a preference for certified public accountants (hereafter: auditors) as assurance providers for sustainability information. The implementation proposals did not make use of the European option to appoint accredited independent assurance providers (hereafter: practitioners). The reason given was that auditors already have an established infrastructure for quality and ethics, and that it would be unrealistic for other practitioners to implement a comparable structure within a short timeframe (Tweede Kamer der Staten-Generaal 2025a). However, to date, the option of appointing practitioners is being explored (Tweede Kamer der Staten-Generaal 2025b).

The CSRD states that the European Commission shall, no later than 1 October 2026, adopt delegated acts in order to provide for limited assurance standards. During the interim period from 2024 to 2026, Member States may use national standards, where available. At the time of the empirical research, the Netherlands could therefore rely on its national sustainability assurance standard (see next subsection). Because not all member states have sustainability assurance standards, the Committee of European Audit Oversight Bodies (CEAOB), at the request of the European Commission, issued non-binding guidelines for limited assurance engagements to facilitate the harmonization of sustainability assurance across the EU (CEOAB 2024). These guidelines take into consideration the IAASB’s work on ISSA 5000 and national guidance of CEAOB members (Kamp-Roelands 2025). The CEOAB was also asked to prepare a technical advice for the development of EU specific add-ons and possible carve-outs to ISSA 5000 to be used for the preparation of the European Delegated Act adopting limited assurance sustainability standards (European Commission 2024b; Kamp-Roelands 2025).

In the Netherlands, the Dutch professional body for accountants (NBA) has issued an assurance standard for sustainability information since 2007: Standard 3810N. The standard is based on the International Standard for Assurance Engagements (ISAE) 3000 of the IAASB (NBA 2024). It was recently updated to incorporate the revised Standard 3000A and the revised Standard 600 (NBA 2024) and earlier to include the IAASB’s Extended External Reporting Assurance Guidance (NBA 2022). As a result, for reporting years 2024, Dutch Standard 3810N reflected the most recent guidance on sustainability assurance.

After the revised Dutch Standard 3810N was published, the IAASB issued in November 2024 the International Standard on Sustainability Assurance 5000 General requirements for sustainability assurance engagements. This provides auditors with guidance on how to perform high quality sustainability assurance engagements and is intended to enhance global harmonization (Kamp-Roelands 2025). Both standards emphasize the clear identification of the subject matter in the assurance report. ISSA 5000 also provides options for elaborating on the conclusion to offer intended users more information and background on the assurance engagement and its conclusion (IAASB 2024; Kamp-Roelands and De Waard 2025). To further promote harmonization between audit firms, the NBA publishes templates for sustainability assurance reports with room for engagement specific circumstances, and a consensus document that provides professional viewpoints on topics where practice may diverge.

Table 1 shows that in 2024 a total of 63 companies obtained assurance (84%). This is an increase compared to 2023, when 45 companies (60%) had assurance on their sustainability information, and compared to reporting year 2020, when 32 companies (43%) obtained assurance (Kamp-Roelands 2022).

Of the 75 listed companies, 63 met the NFRD criteria in 2023 and 65 met the CSRD criteria in 2024. The difference of two companies is explained by the Sif Group that did not fall within the NFRD scope in 2023 (356 employees), but exceeded 500 employees in 2024 and therefore came within the CSRD scope. In addition, AScX newcomer THEON International has more than 500 employees. Five companies that fall under the first tranche of the CSRD did not obtain assurance: Ebusco, which faced financial problems; Renewi, which has a 2024/25 financial year and merge in May 2025; and Azerion and Flow Traders, which note in their annual report that they included sustainability information but did not obtain assurance because the CSRD had not yet been implemented in Dutch legislation. THEON International reports under the NFRD and had not yet obtained assurance. On the other hand, three companies obtained assurance on a voluntary basis: WDP (AMX, part of the sustainability information), FastNed (AScX, specific quantitative indicators), and NSI (AScX, specific quantitative indicators). This may reflect the particular relevance of sustainability issues in the real estate sector (WDP and NSI) and the automotive and infrastructure sector (FastNed).

In 2023, a total of 30 companies (40%) did not obtain any sustainability assurance. For 21 of these companies (4 AEX, 9 AMX and 8 AScX), the CSRD already became applicable in 2024. The other nine companies were part of the group of 12 companies that had until reporting year 2025 to obtain assurance, as they have less than 500 employees (2 AMX and 10 AScX). Also in 2023, the three companies WDP (AMX), FastNed, and NSI (AScX) had already obtained assurance.

In the Netherlands, the largest audit firms have multidisciplinary sustainability assurance teams.³ This means that expertise is available on both the subject matter of assurance and on the requirements for performing assurance engagements. International research shows that combining sustainability assurance engagements with financial statement audits has benefits, such as knowledge deve­lopment and economies of scale (Wallage et al. 2023), the integration of different team member perspectives (Ekasingh et al. 2019), and higher assurance quality (Ruiz-Barbadillo and Martínez-Ferrero 2020). At the same time, experimental research shows that multidisciplinary teams may result in additional costs due to additional review procedures aimed at mitigating overreliance on subject matter experts (Kim et al. 2016).

Table 2 shows that in 2024 all assurance engagements were performed by auditors: 51 Dutch audit firms (81%) and 12 foreign audit firms (19%). None of the assurance engagements was performed by another type of practitioner. The 2023 results show that in the Netherlands, audit firms already dominated the voluntary assurance market for sustainability information, with 35 assurance engagements (78%) performed by Dutch audit firms, eight assurance engagements (18%) by foreign audit firms, and two AEX listed companies using assurance providers with an environmental and/or quality background (Lloyd’ Register and DNV). These firms both originate from the UK, where it is more common for non-audit assurance providers to provide sustainability assurance. In the 2020 research additionally Boskalis used Bureau Veritas Inspection & Certification (Kamp-Roelands 2022). A possible explanation is that the complexity of the environmental aspects at these companies created a preference for specialized environmental agencies.

The results further show that the new CSRD assurance engagements were fairly evenly distributed among the Big 4 (each gaining four additional clients) and that both BDO and Forvis Mazars obtained new clients. During the analysis of the assurance reports it became clear that most of the inconsistencies in the structure and content of the sustainability assurance report were related to the presence of audit firms from different jurisdictions operating in the Dutch sustainability assurance market (2024: 12; 2023: 9 plus two other practitioners) If the European Commission aims to achieve a more harmonized approach to sustainability assurance and communication, it would therefore be important to consider a European template for a sustainability assurance report.

In 2023, the subject matter of sustainability assurance could vary, because there was no legal obligation in the Netherlands to obtain assurance on sustainability information. From reporting year 2024 onwards, this changed as a result of companies applying the CSRD despite the delay in Dutch legislation.

Table 3 shows that in 2024, a total of 57 companies had clearly identifiable CSRD information. One company received the categorization as having ‘full sustainability information’ because it complies with Spanish legislation (implementing the NFRD and the European Taxonomy Regulation). In 2023, ten companies (22%) presented the information subject to assurance in a separate section of the annual report. In total, 20 companies (45%) had the information in 2023 spread throughout the (integrated) annual report. In those cases, the assurance report describes the paragraphs or pages in the annual report subject to assurance, or sometimes refers to markings indicating which information was subject to assurance. Despite such descriptions or markings, it is difficult to identify whether all relevant sustainability information was subject to assurance. The CSRD changed this. If companies choose the ‘by reference’ option instead of a ‘separate section’ option and include sustainability information in different sections of the report, they must include a cross-reference table indicating where the mandatory CSRD information can be found.

In 2023, 15 companies (33%) obtained assurance only on specific indicators. In 2024, this number was reduced to four companies (6%). In these cases, the assurance report includes a (long) list of the indicators. In 2023, for example, Shell’s assurance covered only CO₂ information. In 2024, fewer companies selectively determined the subject matter of assurance as a result of the CSRD. Under the CSRD, all mandatory sustainability information is subject to assurance.

With respect to the completeness of topics, the company’s double materiality analysis (DMA) remains the crux, as it determines which topics are most relevant and therefore what the company reports on. In the 2023 assurance reports analyzed, the procedures performed with respect to the materiality process were often described somewhat hidden in the section “the procedures performed”. For example, the description “gaining an understanding of the reporting process” was used, sometimes with the additional wording “including the assessment of the dialogue with stakeholders”. Given the importance of the DMA, in the CSRD, the process of determining sustainability information has become an explicit part of the subject matter of assurance. In the 2024 assurance reports, the assurance procedures with respect to the DMA are explicitly described in the section “the procedures performed” and address both the process itself as well as the related disclosures. The 2024 results show, however, that auditors often include an emphasis of matter paragraph highlighting the subjectivity of the DMA (see also later in this article).

It is logical to exclude the comparative information for companies that obtain assurance for the first time. The research showed that this was also done by a number of companies that had been reporting for some time. This was seen in the 2023 assurance reports, as well as in the 2024 assurance reports. A possible explanation is that new or adjusted indicators were reported in preparation for the CSRD in 2023 and under the CSRD in 2024.

Table 4 shows that for reporting year 2024, a total of 59 companies obtained limited assurance, four companies obtained a mixed level of assurance (reasonable and li­mited), and none obtained reasonable assurance only. In 2023, three companies still had reasonable assurance engagements (DSM-Firmenich (KPMG), Signify (EY) and Post NL (KPMG)). This was already fewer than in reporting year 2020 (five companies). Two of these companies now obtained a mixed level of assurance and one obtained a limited level of assurance. In addition, in the two mixed assurance engagements, the scope of the reasonable assurance part was further limited to only certain indicators. Philips already had a mixed assurance engagement in 2023 (reasonable assurance on its sustainability information and limited assurance on its Taxonomy information). However, in 2024, it reduced the scope of the reasonable assurance part to only selected information. KPN had mixed assurance both in 2024 and 2023. The other mixed assurance engagements from 2023 were in 2024 reduced to limited assurance engagements (ASR Nederland (KPMG), Air France-KLM (KPMG) and Besi (EY)).

All ‘new’ assurance engagements in both 2024 (18 compared to 2023) and 2023 (12 compared to the previous 2020 research) were aimed at obtaining limited assurance. The results show that although the volume of sustainability assurance engagements increased, the ambition decreased for the level of assurance obtained.

In 2024, 63 companies were required to report under the CSRD. Under the NFRD companies could use several frameworks and standards, such as the GRI. Even when the CSRD is applicable, companies may continue, in the context of international activities, to report under international frameworks (such as GRI) or the standards of the International Sustainability Standards Board (ISSB), in addition to the CSRD and ESRS. This research therefore takes a closer look at which criteria are currently used to evaluate the subject matter of assurance.

Table 5 shows that in 2024 there was much greater consistency in assurance criteria compared to 2023. Although the Netherlands had not yet implemented the CSRD in national legislation, 57 companies referred to the CSRD, ESRS, and the Taxonomy Regulation. The results show that in 2023, although the NFRD had been implemented in Dutch legislation (Article 391, paragraph 5), there was no direct reference to it in the assurance reports, except for one company.

In 2023 the most frequent reference was to GRI and the company’s additional reporting criteria (19 companies, 42%; compared to 2020: 16 companies, 49%). When combinations of GRI with other criteria are included, the total for 2023 increases to 26 companies (58%). Also, in 2023, for 16 companies (36%), the auditor referred exclusively to the company’s own reporting criteria. In 2024, this was reduced to three companies (7%).

Although in 2024 auditors referred to the ESRS and Article 8 of the Taxonomy Regulation, it is remarkable that the companies themselves continued to refer to multiple criteria in their reporting policy section. This suggests that they aim to comply simultaneously with several types of frameworks and standards. However, each reporting framework or standard is designed for a specific purpose, and its information requirements are aimed at providing a specific perspective. Therefore, in my own view, only one primary framework should be used, with other frameworks or standards serving a supplementary role. Currently, many standard-setters emphasize interoperability and show how different criteria overlap or relate to each other.

The addressee of the assurance report is not specified in Dutch Standards 3810N or Standard 3000A, in ISSA 5000, in the CSRD, or in the guidance of the CEAOB. Sustainability information is used by a variety of stakeholders (European Parliament and the Council 2022). The CSRD itself only describes the governance around sustainability reporting, stating that there is collective responsibility of the members of a company’s management, administrative and supervisory bodies (European Parliament and the Council 2022). It also specifies that the supervisory body is responsible for overseeing the sustainability assurance engagement and liaising with the auditor, including nominating the auditor of the sustainability information (European Parliament and the Council 2022). However, although the audit committee, as part of the supervisory body or non-executive board, is the auditor’s primary contact, the assurance engagement is performed on behalf of the intended users of the information. The results in Table 6 show that in both 2024 and 2023, none of the assurance reports referred explicitly to the stakeholders of the sustainability information. Also, the 2020 study found only one such reference by a practitioner. In contrast, Hummel et. al (2019) found in their European sample prior to the NFRD requirements an ave­rage of 13% of firms addressing all stakeholders (note: the Netherlands was not included). They noted that practitioners more often refer to all stakeholders.

Table 6 shows that the majority of assurance reports are addressed to the shareholders and the supervisory board (2024: 34 companies, 53%; 2023: 30 companies, 67%). The exact wording differs somewhat, partly because foreign auditors are active in the Dutch market or because the company itself is foreign. In the Netherlands, a two-tier board structure applies. This is in contrast with many other countries, such as the UK, which have a one-tier board. The results show that since the CSRD, assurance reports are more frequently addressed solely to the executive or management board (2024: 10–16%; 2023: 3–7%) or the supervisory board or board of directors (2024: 6–10%; 2023:3–7%). Addressing the report to the board may relate to limiting liability. This is most clearly illustrated by assurance reports issued by various foreign auditors that explicitly limit the use of the assurance report to the company’s management and even limited responsibility or liability to anyone else using the assurance report. An example can be found in the sustainability assurance report of KPMG in Unilever’s annual report (Quote 1).

Quote 1

Intended use of our report

Our report has been prepared for the Company solely in accordance with the terms of our engagement. We have consented to the publication of our report within the Annual Report and Accounts for the purpose of the Company showing that it has obtained an independent assurance report in connection with the Sustainability Statement. Our report was designed to meet the agreed requirements of the Company determined by the Company’s needs at the time. Our report should not therefore be regarded as suitable to be used or relied on by any party wishing to acquire rights against us other than the Company for any purpose or in any context. Any party other than the Company who obtains access to our report or a copy and chooses to rely on our report (or any part of it) will do so at its own risk. To the fullest extent permitted by law, KPMG LLP will accept no responsibility or liability in respect of our report to any other party. (Unilever, annual report 2024)

The wide variety of addressees in the sample shows that auditors clearly struggle with how to address the assurance report while managing legal responsibility in an area where many different types of stakeholders can be identified as users of sustainability information.

Eumedion, an organization representing Dutch shareholders, notes that the information value of assurance reports would increase if auditors were to include key assurance matters (Eumedion 2025). Key audit matters were introduced in financial auditors’ reports to describe those matters which, in the auditor’s professional judgement, were of most significance in the audit of the financial statements and relevant to communicate to the intended users of the auditor’s report. In a similar way, key assurance matters could be identified in sustainability assurance. Neither ISSA 5000, nor the earlier guidance on ISAE 3000 for extended forms of external reporting (IAASB 2021), nor the current version of the Dutch Standard 3810N provides the option of including key assurance matters in the assurance report.

The results show that in 2024 only one assurance report referred to key assurance matters. Air France-KLM obtained CSRD assurance and included an extensive section on matters that received particular attention. In 2023, eight assurance reports contained a key assurance matter (six AEX listed companies, one AMX listed, and one AScX listed company). In addition, one assurance report mentioned that the inclusion of a key assurance matter was considered, but that none were identified.

The key assurance matters in 2023 concerned:

• AEX: Scope 3 GHG information (Unilever (PwC), KPN (EY), IMCD (Deloitte), impact of the merger and food system commitments (DSM-Firmenich), ASR (scope 1 and 2 emissions of assets under management portfolio for own account (thus scope 3 for ASR) by KPMG), Ahold Delhaize (scope 3 emissions)
• AMX: Signify (scope 3 emissions, circular revenues), by EY
• AScX KAMs considered but none identified, Post NL by KPMG

The limited number of key assurance matters could relate to the discussions on the development of ISSA 5000. These discussions resulted in the decision to not include key assurance matters for the time being, as they could be confusing in combination with the section on procedures performed. Another explanation could be that in 2022 the Dutch NGO Milieudefensie urged the Big 4 audit firms of large polluters to consider a key audit matter for climate change for financial audits (Milieudefensie 2022).

The auditor may include an emphasis of matter paragraph to draw intended users’ attention to a matter presented or disclosed in the sustainability information that, in the practitioner’s judgment, is of such importance that it is fundamental to the users’ understanding of that information (IAASB 2024). Remarkable is that 59 of the assurance reports in 2024 (94%) include an emphasis of matter paragraph (see Table 7). The content most often refers to inherent limitations to the reliability of quantitative data and the DMA (41 times), only the DMA (7 times), or only inherent limitations to the reliability of the data (6). The wording of the emphasis of matter paragraphs is highly standardized with some nuances referring to value chain information, or sometimes to uncertainties in the process of identifying impacts, risks and opportunities, due diligence, or the implementation of new reporting standards. Only for five AMX-listed companies was the emphasis of matter paragraph more specific, referring to the application of the ‘do no significant harm’ criteria in the Taxonomy Regulation, the reporting principles of a subsidiary, a new strategic orientation or the GHG of a particular transaction. In assurance reports issued by some foreign auditors, an emphasis of matter was also included to point to the restriction on the intended user group of the assurance-report.

In 2023 an emphasis of matter paragraph was found in only two assurance reports (4%), both issued by foreign auditors. EY UK included an emphasis of matter in its assurance report to RELX plc’s management regarding an uncertainty in electricity purchased from renewable sources in 2023, as 20% of the renewable energy certificates originated from foreign countries. Deloitte Spain included an emphasis of matter in its assurance report on Allfunds Group to refer to the section on the board of directors’ responsibility for preparing the ESG information of Allfunds Group’s sole subsidiary in compliance with the applicable legal reporting provisions.

The implementation of the CSRD could have led to the expectation that, in 2024, qualified conclusion would be issued more frequently (Kamp-Roelands and de Waard 2025). Potential causes noted were that (1) the information systems for sustainability information may not yet be as robust as for financial information, (2) evidence on certain sustainability information may be difficult to obtain, such as supply chain information, or (3) that diffe­rent interpretations may occur due to the subjective nature of certain information. Therefore, the type of conclusion was included in the research.

The 2023 results in Table 1 show that 21 out of 63 companies that needed to comply with the CSRD in 2024 did not have any assurance, and Table 3 shows that of the 42 companies that did obtain assurance, 13 only obtained assurance on certain indicators. As it takes time to make investments in the reporting process (Kamp-Roelands 2022), this supports the concern that the reporting process could be insufficiently robust when obtaining assurance for the first time in 2024.

The research results show, however, that in 2024 none of the assurance reports included a qualified conclusion. This implies that auditors were able to collect sufficient and appropriate evidence to support their conclusion, that any uncertainties identified were not material enough to impact their conclusion, and that there were no material disagreements with clients on compliance with the criteria such as for measurements or calculations. The combination of no qualified conclusions and the large increase in emphasis of matter paragraphs may indicate that auditors requested clients to describe uncertainties regarding sustainability information so they could be referenced in the assurance report. The question remains, however, how large such uncertainties can be before they should result in a qualified conclusion. The Dutch Authority Financial Markets acknowledges a growth path for large listed companies and audit firms and continues to support preparation for CSRD reporting through studies and publications.⁴ This may have contributed to auditors adopting a growth path approach.

In 2023 two assurance reports included a qualified conclusion. KPMG qualified its conclusion for the scope 3 emissions of DSM-Firmenich due to uncertainty regarding the completeness of the scope 3 data. Scope 3 emissions are based, among other things, on spend data and emission factors. KPMG identified limitations with respect to the reconciliation of the spend data with the financial information underlying DSM-Firmenich’ consolidated 2023 financial statements, due to the merger. The sustainability information covered the full calendar year, while the financial statements are consolidated as from the merger date. The other qualification concerned KPMG’s conclusion for ASR Nederland, which relates to insurance-related emissions.

Based on the sustainability assurance reports analyzed for 2023 the conclusion (when the subject matter of assurance was most or all sustainability information), most often issued in the Netherlands concerned wordings rela­ted to the view presented by the information as a whole, such as:

Based on our procedures performed and the assurance information obtained, nothing has come to our attention that causes us to believe that the selected sustainability information does not present fairly, in all material respects:

• The policy with regard to sustainability matters
• The business operations, events and achievements in that area in 2023 in accordance with the applicable criteria as included in the section Criteria.

The text for the conclusions were inspired by the NBA template, although it was apparent that while various sustainability assurance reports used the word ‘fairly’, the NBA template itself used the wording ‘reliable and adequate view⁵.

Where the subject matter was only selected indicators the wordings in the conclusion solely related to ‘prepared in accordance with’.

For the 2024 assurance reports, the European Commission provided an example conclusion in their Questions & Answers on the CSRD (European Commission 2024a, Q 70). CEOAB guidance (CEAOB 2024, p. 8) suggested: ‘no matter has come to our attention to cause us to believe that the information included in the sustainability statement is not fairly presented, in all material respects, in accordance with ESRS and that it is not compliant with the legal requirements of Article 8 of the Taxonomy Regulation’. The results in Table 8 show that none of the auditors used this example conclusion. In total, 57 reports included expressions such as “in accordance with the criteria and compliant with”. Minor variations were observed: some auditors noted that “the DMA was in accordance with..”, while others noted that “the DMA was in compliance with… “. Also some only noted that the DMA was in accordance with the description by the company. This is different from the CSRD’s perspective, which is to assess the process carried out by the undertaking to identify the information reported pursuant to those sustainability standards. (CSRD art. 34.)

The results show that auditors have moved away from the wording “fairly present[ing] the subject matter of assurance in accordance with the Criteria” to the wording “prepared in accordance with the Criteria”. Accountancy Europe notes the various reservations on the concept of “fair presentation” in the draft amended ESRS, including the greater responsibility for boards and auditors and the increase of risk of litigation (Accountancy Europe 2025). The six engagements with a different type of conclusion are consistent with the six engagements that have a different subject matter than the CSRD information.