The International Ethics Standards Board for Accountants (IESBA) has published two new staff documents intended to clarify and promote the understanding of its ethics standard regarding the use of external experts, as well as the International Ethics Standards for Sustainability Assurance (IESSA).

These documents will come into effect in December 2026.

The publications detail important elements of the standard related to the engagement of external experts and the proportionality of ethics and independence requirements for sustainability assurance as outlined in the IESSA.

Designed for all professional accountants, whether operating in business or public practice, as well as sustainability assurance practitioners (SAPs), the documents address frequently asked questions.

These include considerations when deciding to utilise the work of an external expert, methods for identifying suitable external experts, and the additional requirements for assessing the objectivity of an external expert in the context of audit or assurance engagements, including those related to sustainability.

It further discusses how to evaluate an external expert’s competence, capabilities and objectivity, potential threats associated with relying on their work, factors concerning the IESSA, and access to additional resources available on the IESBA Experts Page.

Moreover, the documents underscore key features of the IESSA that reflect its proportionality, establishing a comprehensive global ethics and independence framework for sustainability assurance engagements (SAEs).

This proportionality is intended to facilitate the execution of SAEs across entities of varying sizes, thereby enhancing public confidence in these engagements.

The guidance particularly aims to assist small and medium-sized practices in implementing the IESSA within the sustainability assurance field.