Sustainability Reporting Assurance
Updated May 2026
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.
On March 9, 2026, the Auditing and Assurance Standards Board (AASB) adopted the ISSA 5000 as the Canadian Standard on Sustainability Assurance (CSSA) 5000, with Canadian-specific amendments to the effective date and alignment with Canada’s ethical requirements.
Prior to the effective date of CSSA 5000, assurance engagements over sustainability information were performed under:
- 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
Once CSSA 5000 becomes effective on December 15, 2027, CSAE 3410 will be withdrawn and CSAE 3000 may no longer be used for sustainability assurance engagements.
When is CSSA 5000 Effective?
CSSA 5000 is effective for assurance engagements on sustainability information reported for periods beginning on or after December 15, 2027, or as at a specific date on or after December 15, 2027. Early application is permitted.
Who's impacted?
All sustainability assurance practitioners, as well as preparers and users of sustainability information seeking investor-grade assurance.
What’s the latest?
CSSA 5000 was issued on March 9, 2026 without the Canadian amendment related to Indigenous matters. The AASB is currently deliberating feedback on 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 final approval is anticipated by spring 2027.
What do Canadian CPAs need to know?
CSAA 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.
Where can I learn more?