Australia’s mandatory climate reporting era has officially begun.
The country’s largest companies have now lodged their first reports under the Australian Sustainability Reporting Standards, anchored by Australian Accounting Standards Board Standard S2 (AASB S2).
To understand where your business sits, it helps to know how the reporting groups are defined.
- Group 1 captures Australia’s largest companies
Those meeting at least two of three size thresholds (revenue of $500 million or more, gross assets of $1 billion or more, or 500-plus employees), plus any organisation reporting under the National Greenhouse and Energy Reporting Act that exceeds 50,000 tonnes of carbon dioxide equivalent emissions regardless of size. These companies have now completed their first mandatory climate disclosures.
- Group 2 companies
Those with revenue of $200 million or more, gross assets of $500 million or more, or 250 or more employees (meeting at least two of the three), begin reporting for the financial year starting 1 July 2026.
- Group 3 captures the next tier
Companies with revenue of $50 million or more, gross assets of $25 million or more, or 100 or more employees (again, at least two of the three). Their first reporting year begins 1 July 2027.
Businesses that wait until late 2026 to start will be paying a premium for scarce expertise, scrambling on documentation, and running out of runway.
What Australia’s first climate reporters learned the hard way
Australia made history as the first country to mandate International Sustainability Standards Board-based climate disclosures.
Group 1 companies had no precedent to follow, no comparable reports to benchmark against, and a standard that proved technically and operationally demanding.
Here’s what they discovered:
- Get the right team in the room early. The companies that fared best stood up a cross-functional governance structure from the outset, bringing sustainability, finance, and legal together under a clear delegated framework.
- Documentation is everything. The Australian Securities and Investments Commission is reading these reports carefully and has already flagged discrepancies between climate disclosures and historical financial statements. Auditors are requesting workshop records, meeting agendas, and decision trails. If you can’t show your workings, your disclosure is exposed. Transparency about methodology, including what scenarios you chose and why, is not optional.
- Consistency across all your disclosures. The sustainability report and the financial report must be read as one document. Anything said in voluntary marketing reports, investor presentations, or global disclosures needs to hold up against what’s in the AASB S2 filing. Contradictions create legal and reputational risk.
- Shorter is better. The best reports were tight and specific to the business. Some Group 1 reports ran over 80 pages; the better ones landed around eight. This is not a voluntary sustainability brochure.
- Start earlier than feels necessary. Every company that struggled did so because they underestimated the data collection burden and left too little time to engage their assurance provider before crunch point.
The stakes are real
AASB S2 is not a voluntary framework with soft consequences. The obligations are legally binding and carry genuine personal and commercial risk:
- Limited assurance is required from the first reporting year, expanding to all disclosures in year two
- Full reasonable assurance becomes mandatory from 2030
- Directors must personally declare that the sustainability report complies with AASB S2
- Non-compliance carries penalties of up to $16.5 million or 10% of annual turnover. There is a three-year safe harbour in place as the reporting regime settles in.
The cost shock
Unlike financial auditing, climate reporting and assurance is an emerging discipline with limited supply and rising demand. Preparing a compliant climate disclosure, even using artificial intelligence-enabled tools, can cost up to $100,000 before internal resourcing is factored in.
The documentation burden compounds this.
Businesses that build disciplined records now, before any reporting obligation lands, reduce their assurance costs materially when the time comes.
Beyond compliance: the commercial case for getting ahead
For businesses that move early across all areas of ESG, the reward extends beyond regulatory compliance.
Australia’s major resources operators, including BHP, Rio Tinto, Woodside, and Chevron, now embed sustainability, modern slavery, and environmental criteria into their supplier pre-qualification portals as standard.
For further guidance, the Australian Accounting Standards Board has published a dedicated AASB S2 knowledge hub.
Ready to get ahead of it?
At Collage & Co, we work with businesses to make environmental, social and governance reporting and climate disclosure practical, proportionate, and commercially useful. Whether you’re mapping your carbon baseline for the first time or building out a full AASB S2 readiness plan, we bring the strategy, the process, and the right tools to make it manageable.
We partner with Trace, an Australian climate reporting platform purpose-built for AASB S2 compliance. Trace brings carbon measurement, climate risk and scenario analysis, and AASB S2 disclosure output together, turning climate reporting from a one-off scramble into a repeatable annual process.
Together, we take the complexity out of climate reporting and help you turn a compliance obligation into a business advantage.
To understand what AASB S2 means for your business, reach out at to the team at Collage & Co at info@collageandco.com.au or contact Ledge Finance to get started.
