Assurance of Sustainability Reporting


    General overview of the assurance engagement

    In Luxembourg, an approved statutory auditor (réviseur d’entreprises agréé) or an approved audit firm (cabinet de révision agréé) (which may be the one that carries out the statutory audit of the financial statements or another) is required to provide assurance on the sustainability report and to express an opinion as regards :

    • The compliance of the sustainability report with the requirements of the accounting laws;
    • The compliance of the sustainability report with the ESRS;
    • The compliance of the process carried out by the undertaking to identify the information reported pursuant to the ESRS;
    • The compliance with the requirement to mark-up the sustainability report;
    • The compliance with the reporting requirements provided for in Article 8 of the Regulation (EU) 2020/852.

    The results of the assurance of sustainability report, including the opinion referred to above, are presented in an assurance report which may be included as a separate section of the audit report or in a separate assurance report.

    This assurance engagement shall be performed in accordance with the requirements of the limited assurance standards1 adopted by the European Commission no later than 1 October 2026.

    As long as the European Commission has not adapted an assurance standard, there will be a transition period during which Member States may adopt national standards or position statements. In order to facilitate harmonisation of the assurance standards being applied in the Member States during this transition period, the European Commission has invited the le Committee of European Auditing Oversight Bodies (CEAOB)  to develop non-binding guidelines to define the procedures to be performed when providing this assurance report.

    In Luxembourg, the CSSF will publish these guidelines as soon as they have been approved by the CEAOB and subject to public consultation.

    1 In accordance with the 2nd paragraph of point 3 of Article 26a of Directive 2006/43/EC as amended, the European Commission will assess before 1 October 2028 whether reasonable assurance is feasible for auditors and companies.


    In order to carry out this assignment, an approval shall be granted by the CSSF to the statutory auditor (réviseur d’entreprises) satisfying all the following conditions:

    • Have a professional establishment in Luxembourg;
    • Be approved to carry out statutory audits;
    • Provide proof of professional qualification to carry out the assurance of sustainability information, in accordance with the forthcoming Grand Ducal regulation on professional qualification.

    Similarly, in order to be able to carry out these assignments, audit firms (cabinet de révision) shall be approved by the CSSF when the following conditions are met:

    • Be approved to carry out statutory audits;
    • The natural persons who carry out the assurance on sustainability report on behalf of the legal person must have the required approval;
    • A majority of the voting rights must be held by persons holding both approvals for the statutory audit and for the assurance of sustainability information;
    • A majority of the members of the administrative or management body must be persons with both the statutory audit and sustainability assurance approvals.

    Transitional period

    Statutory auditors (réviseurs d’entreprises agréés) approved before 1 January 2024 to carry out statutory audits are not subject to the professional qualification requirements to be approved to carry out sustainability assurance. However, they will have to acquire the necessary knowledge through continuing professional development before 1 January 2026.

    The same applies to all natural persons who, on 1 January 2024, are candidates to access the audit profession or statutory auditor (réviseur d’entreprises), provided that they complete the procedure for approval to carry out statutory audits before 1 January 2026.

    Professional qualification requirements

    From 1 January 2026, in order to carry out sustainability assurance, an approved statutory auditor will have to meet the following additional specific requirements:

    • Provide evidence of theoretical qualification ;
    • Complete a professional internship of at least eight months in the field of sustainability information assurance or other sustainability-related services;
    • Pass the complementary professional competence examination..

    Quality Assurance System

    Approved statutory auditors (réviseurs d’entreprises agréés) and approved audit firms (cabinets de révision agréés) are subject to a quality assurance system for the engagements they perform in the context of statutory audits and sustainability report assurance.

    Quality assurance reviews are carried out on the basis of a risk analysis and at least every six years.


    Laws, regulations and directives