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Sustainability Reporting Assurance

This page is your simple guide to understanding the standards that underpin assurance in sustainability reporting.

What is sustainability reporting assurance?

Like assurance on financial information (e.g., financial statements), sustainability assurance involves an independent third-party performing procedures to verify the reliability and credibility of an organization’s sustainability information and to report on the information. Assurance providers provide either reasonable or limited assurance opinions on sustainability information.

Why is assurance of sustainability information important?

External assurance is important to enhance trust and confidence in sustainability reporting. External assurance can also help organizations improve their reporting processes, data management and accountability.

What sustainability assurance standards exist?

There are a couple of assurance standards that support sustainability reporting. Currently, Canadian Standard on Assurance Engagements (CSAE) 3000, Attestation Engagement other than Audits and Reviews of Historical Financial Information and CSAE 3410, Assurance Engagements on Greenhouse Gas Statements are available for use of sustainability information. Furthermore, the International Auditing and Assurance Standards Board (IAASB) has released an assurance standard specific to sustainability, International Standard on Sustainability Assurance (ISSA) 5000, General Requirements for Sustainability Assurance Engagements.

ISSA 5000

On November 12, 2024, the IAASB issued ISSA 5000. The standard is a comprehensive, stand-alone standard for all assurance engagements (both reasonable and limited assurance engagements) on sustainability information. It applies to sustainability information reported across any sustainability topic and prepared under any sustainability reporting framework. The standard is also profession agnostic, supporting its use by both professional accountant and non-accountant assurance practitioners.

The Canadian Auditing and Assurance Standards Board (AASB) issued in September 2023 the Canadian Standard on Sustainability Assurance (CSSA) 5000 exposure draft, which is based on ISSA 5000 with amendments considered appropriate for the Canadian market. The CSSA 5000 exposure draft (ED-CSSA 5000) was open for comment until December 31, 2023. The AASB released a summary of feedback from the outreach efforts related to the ED-CSSA 5000.

Adjacent to the work of the IAASB and AASB, the International Ethics Standards Board for Accountants (IESBA) resolved in June 2022 to take action to develop fit-for-purpose, globally applicable ethical and independence standards to support sustainability reporting. In December 2024 the IESBA approved the new International Ethics Standards for Sustainability Assurance (“IESSA”) for use by all sustainability assurance practitioners. Go to “Sustainability - Professional Ethics” section for more information.

Who's impacted?

As the ISSA 5000 standard is adopted in Canada in the form of the CSSA 5000, entities that are currently obtaining assurance over sustainability information or are contemplating obtaining assurance on sustainability information under the extant standard, Canadian Standard for Audit Engagements (CSAE) 3000, Attestation Engagements Other than Audits or Reviews of Historical Financial Information, may find themselves impacted when CSSA 5000 takes effect.

Entities obtaining a separate assurance conclusion on greenhouse gases (GHGs) under CSAE 3410, Assurance Engagements on Greenhouse Gas Statements, will continue to be available.

What’s the latest?

In its December 2024 meeting, the AASB decided to re-expose the CSSA 5000 concerning Indigenous matters, due to its intention to conduct further outreach and gather additional feedback on the developments since ED-CSSA 5000. The re-exposure draft is expected to be publicly available for input in Spring 2025.

What do Canadian CPAs need to know?

Currently, there are no mandatory sustainability reporting and assurance requirements in Canada. However, the draft US climate disclosure Rule proposes assurance for certain disclosures, and the EU’s Corporate Sustainability Reporting Directive (CSRD) requires limited assurance on sustainability information with a move to reasonable assurance in the future. Please refer to At a Glance: Sustainability Reporting Standards and Regulations for more information.

CSSA 5000 is not yet finalized, or effective. In the meantime, there are other assurance standards that can provide assurance for sustainability information, such as:

Canadian Standard on Assurance Engagements (CSAE) 3000, Attestation Engagement other than Audits and Reviews of Historical Information
CSAE 3410, Assurance Engagements on Greenhouse Gas (GHG) Statements

Where can I learn more?

For more information, please refer to our FAQs on the sustainability assurance landscape.

You can also refer to:

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