Sustainability Reporting Assurance
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?
In November 2024, the International Auditing and Assurance Standards Board (IAASB) released an assurance standard specific to sustainability, International Standard on Sustainability Assurance (ISSA) 5000, General Requirements for Sustainability Assurance Engagements.
The Canadian equivalent to ISSA 5000 is the proposed Canadian Standard on Sustainability Assurance (CSSA) 5000. It is based on ISSA 5000 with amendments considered appropriate for the Canadian market. However, the proposed CSSA 5000 is not yet finalised.
In the meantime, there are other Canadian assurance standards that can be used to provide assurance on sustainability information:
- Canadian Standard on Assurance Engagements (CSAE) 3000, Attestation Engagement other than Audits and Reviews of Historical Financial Information
- CSAE 3410, Assurance Engagements on Greenhouse Gas Statements are available for use on sustainability information
Who's impacted?
Entities that are currently obtaining assurance over sustainability information and sustainability assurance providers.
What’s the latest?
On April 30, 2025, the AASB published the Re-exposure Draft: Canadian Amendments Related to Indigenous Matters in the Canadian Standard on Sustainability Assurance (CSSA) 5000, General Requirements for Sustainability Assurance Engagements. The comment period closed on July 18, 2025.
In May 2025, following the approval of ISSA 5000, the IAASB announced the withdrawal of International Standard on Assurance Engagements (ISAE) 3410, Assurance Engagements on Greenhouse Gas Statements. The withdrawal of ISAE 3410 will take effect from the effective date of ISSA 5000.
Similarly, ISAE 3000 (Revised) Attestation Engagement other than Audits and Reviews of Historical Financial Information will no longer be applicable for sustainability assurance engagements after the effective date of ISSA 5000.
What do Canadian CPAs need to know?
ISSA 5000 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. ISSA 5000 is effective for assurance engagements on sustainability information reported for periods beginning on or after December 15, 2026, or as at a specific date on or after December 15, 2026. Early application is permitted.
CSSA 5000 is not yet finalized, or effective. In the meantime, Canadian entities and their assurance providers may choose to use ISSA 5000 or CSAE 3000 and CSAE 3410 as appropriate for their sustainability assurance needs.
Currently, there are no mandatory sustainability reporting and assurance requirements in Canada. However, regulations in other global jurisdictions may have assurance requirements that may affect Canadian companies within their scope. Please refer to At a Glance: Sustainability Reporting Standards and Regulations for more information.
Where can I learn more?