The Carbon Trust
Explained byThe Carbon Trust

Identify the assurance requirements required by your chosen reporting mechanisms

Most reporting mechanisms require disclosures to be verifiable, and many recommend some form of assurance

The reporting mechanism your business adheres to may have specific requirements or recommendations when it comes to assurance. The following table summarizes the assurance requirements relating to the sustainability reporting mechanisms discussed in Step and 2:

Figure 6: The assurance requirements under key reporting mechanisms

Most standards and frameworks recommend some form of external verification to improve the credibility and usefulness of sustainability data and claims. However, regulations can also make assurance a legal obligation. As such, it is important to consult local legislation to identify specific requirements for companies in your jurisdiction. As outlined in the table above, companies in the UK, EU, and US should comply with the assurance practices set out by TCFD, CSRD, and SEC, respectively. Other jurisdictions, including India, New Zealand, and Singapore, have mandatory assurance requirements for sustainability reporting.

Assurance requirements of key reporting mechanisms

CSRD Assurance

Your organisation must obtain limited assurance, from the first year of reporting in line with CSRD.

This should be carried out by your company’s statutory auditor, for consistency and connectivity between financial and sustainability data. However, individual Member States can also permit independent assurance providers (or other statutory auditors) to provide this assurance, if they comply with the assurance quality standards set by the European Commission.

The auditor will express an opinion as to whether your sustainability reporting, and processes to produce disclosures (e.g. your materiality assessment) comply with the CSRD’s standards.

The assurance opinion should be publicly available, published together with your annual financial report.

The European Commission is also exploring the feasibility of introducing a requirement for reasonable assurance at a later date. The Commission may also adopt specific standards for limited assurance, by 1 October 2026. Member States can also implement national standards, provided that the European Commission has not already adopted assurance standards covering the same subject matter.

As well as monitoring sustainability reporting processes, your organisation’s audit committee will be responsible for informing the administrative or supervisory body of the outcome of the sustainability reporting assurance, monitoring the independence of the assurance provider.

ISSB Assurance

ISSB standards are less prescriptive about assurance. They stipulate that:

  • When reporting Scope 3 emissions, your organisation must prioritise data that has been verified, although this can include internal verification

  • Your organisation must disclose whether its climate targets and target-setting methodology have been validated by a third party