The IAASB's ISSA 5000 and the IESBA's IESSA constitute a cohesive package of global standards for sustainability assurance that responds to market demand and calls from regulators and other stakeholders for reliable, credible, comparable, and trustworthy sustainability information.

This summary provides a technical overview of the International Ethics Standards Board for Accountants' (IESBA) pronouncement Using the Work of An External Expert.

To support practitioners, the IAASB has released this Frequently Asked Questions document to address specific questions stakeholder may have.

Explore other IAASB implementation and support materials at www.iaasb.org/ISSA 5000, including our new FAQ video series.

The International Auditing and Assurance Standards Board (IAASB) and the International Ethics Standards Board for Accountants (IESBA) today launched an integrated effort to support effective implementation of their landmark standards aimed at advancing trust and transparency in sustainability reporting and assurance.

Taken together, the IAASB and IESBA sustainability-related standards, as well as the new IESBA standard on using the work of experts, provide a unified global approach to address the growing demand for trustworthy sustainability information to support stakeholder decisions.

These standards establish clear expectations for ethical behavior in sustainability reporting and assurance and provide more specific requirements for practitioners and organizations in relation to assurance engagements on sustainability information. The IAASB’s ISSA 5000 and the IESBA’s IESSA share five common goals:

• Equipping global markets with a cohesive package of standards. After robust and close coordination, the IAASB and IESBA developed comprehensive, interoperable global standards for assurance, ethics, and independence for sustainability assurance engagements.
• Offering a global baseline and leveling the playing field by meeting market demands and regulatory calls and expectations for profession-agnostic global standards.
• Providing a framework-neutral approach that allows ISSA 5000 and IESSA to be applied in relation to sustainability information prepared under any suitable sustainability reporting framework.
• Promoting informed decision-making based on trust and independently assured sustainability information.
• Mitigating risks of fraud, including greenwashing, and non-compliance with laws and regulations.

A Unified Vision for Sustainability Reporting

“The interoperable package of ISSA 5000 and IESSA represents an important evolution in global sustainability reporting and assurance,” said Tom Seidenstein, Chair of the IAASB. “These standards establish the necessary technical and ethical pillars to ensure that qualified practitioners could consistently perform high-quality assurance engagements on sustainability information.”

Gabriela Figueiredo Dias, Chair of the IESBA, added, “Ethics is the foundation of trust. With these standards, we are equipping preparers and practitioners with the tools needed to uphold integrity and foster transparency in sustainability reporting. Together, the IAASB and IESBA are setting a global standard for accountability and professionalism.”

Effective Dates and Next Steps

In jurisdictions adopting the standards, both ISSA 5000 and IESSA become effective for periods starting on or after December 15, 2026, with early adoption permitted and encouraged. The IAASB and IESBA will provide ongoing support through webinars, implementation guidance, and continued implementation monitoring and feedback channels to ensure smooth and effective adoption.

Stay updated by following IAASB and IESBA on LinkedIn or registering and subscribing to receive announcements directly in your inbox. For more information, visit the joint IAASB and IESBA web page: www.ethicsandaudit.org/TrustInSustainability

ADDITIONAL INFORMATION

IAASB’s ISSA 5000: A Framework for Credible Sustainability Assurance

International Standard on Sustainability Assurance 5000 (ISSA 5000) provides a principles-based framework for conducting assurance engagements on sustainability information reported by entities. The standard is designed to:

• Enhance Reliability and Transparency: Focused on enhancing the credibility of sustainability information reported, ISSA 5000 addresses the growing need for assured sustainability information among investors, regulators, and stakeholders.
• Adapt to Global and Local Contexts: The standard is scalable and adaptable to regional regulatory requirements, such as the EU’s Corporate Sustainability Reporting Directive (CSRD), and can be used with any sustainability reporting framework, standard or other suitable criteria.
• Support Diverse Practitioners: Applicable to all assurance providers, ISSA 5000 ensures consistency and rigor, incorporating materiality concepts and proportionality for organizations of all sizes.

To support practitioners, the IAASB has released new guidance today, including an implementation guide, fact sheet, FAQs, and FAQ video series, and will hold a webinar series in the coming months.

IESBA’s Global Ethics Sustainability Standards: A Foundation for Ethical Mindset and Trust

The International Ethics Standards for Sustainability Assurance (including International Independence Standards (IESSA), the provisions related to sustainability reporting, and the new standards addressing using the work of an external expert in the International Code of Ethics for Professional Accountants (including International Independence Standards), establish a strong ethical foundation for sustainability reporting and assurance engagements. The standards are grounded in the fundamental ethical principles for reporting and assurance that underpin the provision of high-quality sustainability information by:

• Offering a coherent ethical infrastructure for sustainability reporting and assurance that is fit-for-purpose. The standards specifically address challenges inherent to sustainability information, such as the use of immature data and systems, and the forward-looking nature of the information.
• Mitigating unethical conduct, including greenwashing risks, particularly by raising awareness of ethical threats and helping practitioners address challenges such as: non-compliance with laws and regulations^TM (NOCLAR^®); pressure to act unethically; independence issues; and ethical risks relating to using the work of external experts.
• Enhancing investor protection and building trust in sustainability information by aligning best ethical practices among all practitioners.
• Promoting judgments and decision-making that help prevent reputational risks, foster an ethical mindset, and attract skilled and purpose-driven professionals.

Alongside today’s published standards, the IESBA has released Basis for Conclusions documents, fact sheets and technical overviews on the standards. Additional implementation support material and activities, including a series of webinars (see below) and implementation guides, will follow in the near future.

Upcoming IESBA Webinars 

To help stakeholders understand and use the new standards, the IESBA is holding a series of webinars at various times to accommodate a global audience. 

• IESBA Sustainability-related Ethics and Independence Standards 
  • IESBA Sustainability Overview and Sustainability Reporting 
    • February 18 at 14.00 UTC (9.00am ET)
    • February 26 at 01.00 UTC (8.00pm ET February 25)
  • Key Topics in the IESSA 
    • February 19 at 14.00 UTC (9.00am ET)
    • February 27 at 00.00 UTC (7.00pm ET February 26)
  • IESSA Independence Standards: A Deep Dive 
    • February 20 at 13.00 UTC (8.00am ET)
    • February 28 at 00.00 UTC (7.00pm February 27)
• Using the Work of an External Expert
  • March 3 at 23.00 UTC (6.00pm ET) 
  • March 4 at 13.00 UTC (8.00am ET) 

About IAASB and IESBA
The International Auditing and Assurance Standards Board and the International Ethics Standards Board for Accountants are part of the International Foundation for Ethics and Audit (IFEA), a nonprofit organization that supports high-quality, international ethics, audit, and assurance standards in the public interest. The IAASB and IESBA develop and issue their standards independently and in accordance with an approved due process and the Public Interest Framework, overseen by the Public Interest Oversight Board.

The IAASB develops auditing, assurance, related services, and quality management standards and guidance in the public interest that support consistent performance of quality engagements.

The IESBA is an independent global standard-setting board. The IESBA’s mission is to serve the public interest by setting high-quality, international ethics (including independence) standards as a cornerstone to ethical behavior in business and organizations, and to public trust in financial and non-financial information that is fundamental to the proper functioning and sustainability of organizations, financial markets and economies worldwide.

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The International Ethics Standards for Sustainability Assurance (including International Independence Standards) and related revisions to the Code, address critical risks to the integrity, quality and effectiveness of sustainability reporting and assurance such as bias, conflicts of interest, pressure to act unethically, fraud including greenwashing, non-compliance with laws and regulations, and threats to the independence of the assurance practitioners.

The International Ethics Standards Board for Accountants (IESBA) welcomes the Public Interest Oversight Board’s (PIOB) important decision to certify its Global Ethics Sustainability Standards and the International Organization of Securities Commissions (IOSCO) Statement of Support calling on its members to apply or be informed by the new framework. 

The Global Ethics Sustainability Standards include the International Ethics Standards for Sustainability Assurance (including International Independence Standards) (IESSA) and the revisions to the International Code of Ethics for Professional Accountants (including International Independence Standards) (the Code) related to sustainability reporting and to the use of the work of an external expert.

Reacting to the PIOB’s Certification and IOSCO’s Statement of Support, Gabriela Figueiredo Dias, Chair of IESBA said:

“The certification of IESBA’s new ethics standards framework for Sustainability and Experts, along with IOSCO's call for its members to adopt or be informed by the framework, marks a significant step to cement ethics as the foundation of trust and accountability in sustainability reporting and assurance. The global sustainability standards infrastructure is now complete, with the ethics piece providing foundational instruments to underpin transparent, relevant and trustworthy sustainability information. Looking forward to the joint launch with IAASB of the new ethics and assurance standards. Join us on 27 January.”

These landmark new standards provide a robust ethical framework for reporting and assuring sustainability-related information that promotes high quality, reliable information for decision-making by investors, lenders, customers, suppliers, government, regulators and other stakeholders.  

The IESSA and related revisions to the Code, including regarding using the work of an external expert, address critical risks to the integrity, quality and effectiveness of sustainability reporting and assurance such as bias, conflicts of interest, pressure to act unethically, fraud including greenwashing, non-compliance with laws and regulations, and threats to the independence of the assurance practitioners.

The final standards can be found on the IESBA’s website https://www.ethicsboard.org/standards-pronouncements.

The official launch of the new standards will take place on January 27, 2025, jointly with the International Auditing and Assurance Standards Board’s (IAASB) International Standard on Sustainability Assurance 5000 (ISSA 5000). After robust and close coordination, the IESBA and IAASB developed comprehensive, interoperable global standards for assurance, ethics, and independence for sustainability assurance engagements.           

The Using the Work of an External Expert Final Pronouncement provides an ethical framework to guide professional accountants or sustainability assurance practitioners, as applicable, in evaluating whether an external expert has the necessary competence, capabilities and objectivity in order to use that expert’s work for the intended purposes. The standard also include provisions to aid in applying the Code’s conceptual framework when using the work of an external expert.