As mandatory climate-related reporting commences in Australia and continues to mature in New Zealand, reporting entities need to be able to substantiate what they disclose. This means maintaining a clear record of the data, assumptions, judgements, methodologies, review and approvals that support each material disclosure.

CA ANZ’s guide, Substantiating climate-related disclosures: A practical documentation guide for climate reporting entities, provides principles-based guidance to help entities design or uplift documentation policies, procedures and internal controls that create a credible, defensible and reviewable evidence base.

Why this matters now

Climate-related disclosures often involve estimates, assumptions, forward-looking information and entity-specific judgement. This creates a need for documentation that goes beyond the disclosure itself and captures the rationale, evidence and decision-making process behind it.

Effective documentation supports:

• compliance with record-keeping and regulatory requirements
• governance, oversight, review and approval by boards and governing bodies
• assurance readiness by enabling reviewers to follow the evidence trail without reconstructing the work

Building a traceable evidence base

The guide emphasises proportionate, well-governed documentation practices that link key inputs, assumptions, judgements and decisions to the final disclosure, rather than prescribing a single method, system or template.

What the guide covers

The guide provides practical guidance on:

• identifying the inputs, assumptions, judgements and estimates that support each material disclosure
• applying stronger documentation to areas involving higher judgement, uncertainty, estimation or reliance on external data
• assigning clear ownership, review, challenge and approval responsibilities across the reporting process

It also highlights practical steps such as preparing a basis of preparation for key assumptions and methodologies, and maintaining an indexed, version-controlled evidence repository.

Find out more

For practical, principles-based guidance on building documentation processes that support credible and defensible climate-related disclosures, read the full guide below.