AASB S2: What Australian Companies Must Do Before Their First Report
Australia climate reporting has moved from voluntary aspiration to statutory obligation. Since the Treasury Laws Amendment (Financial Market Infrastructure and Other Measures) Act 2024 inserted sustainability reporting into Chapter 2M of the Corporations Act, in-scope entities must prepare a sustainability report as part of their annual report, with climate disclosures made in accordance with AASB S2 Climate-related Disclosures. The largest companies are already working through their first cycle. For the much larger population in Groups 2 and 3, the central point is a simple one. The work that determines the quality of a first AASB S2 report happens in the twelve months before the reporting period begins, not in the weeks before lodgement.
Determining your Group: thresholds and start dates
The regime is phased across three cohorts. An entity falls into a Group if it meets at least two of three size tests, or if it satisfies specific emissions or asset owner criteria.
Group 1 applies to financial years beginning on or after 1 January 2025. It captures entities meeting two of the following: consolidated revenue of at least $500 million, consolidated gross assets of at least $1 billion, or at least 500 employees. Entities reporting under the National Greenhouse and Energy Reporting (NGER) scheme above the publication threshold are also included.
Group 2 applies to financial years beginning on or after 1 July 2026. The thresholds fall to revenue of $200 million, gross assets of $500 million and 250 employees. All other registered NGER reporters, and asset owners such as superannuation funds and registered schemes with $5 billion or more in assets, also enter at this stage.
Group 3 applies to financial years beginning on or after 1 July 2027, at thresholds of $50 million in revenue, $25 million in gross assets and 100 employees. Group 3 entities that conclude they face no material climate-related risks or opportunities may make a statement to that effect rather than full disclosures. That relief is narrower than it appears. The conclusion must be reasoned, documented and defensible, and it will draw scrutiny precisely because it is the exception.
A practical observation follows. Many entities assume they belong to a later Group without testing the consolidated position. Revenue and assets are measured at the consolidated level, and employee numbers include those of controlled entities. Groups with Australian operations owned by offshore parents, and private companies that report under Chapter 2M, should test their classification formally rather than infer it.
What AASB S2 actually requires
AASB S2 is closely based on IFRS S2, with Australian modifications. Disclosures follow the familiar four pillars of governance, strategy, risk management, and metrics and targets. Three requirements consistently prove the most demanding.
First, climate-related scenario analysis. Entities must assess climate resilience against at least two scenarios, one consistent with limiting warming to 1.5°C and one well above 2°C. This is a strategic exercise, and boards that treat it as a modelling task delegated to consultants tend to produce disclosures that fail to connect with the business plan.
Second, greenhouse gas emissions. Scope 1 and 2 emissions are required from the first year. Scope 3 emissions are required from the second reporting period, but the data infrastructure must be in place well before then. Value chain data from suppliers and customers rarely arrives on request, and entities that leave supplier engagement until year two will report estimates they cannot easily defend.
Third, transition plans and targets. Where an entity has a transition plan or climate targets, it must disclose them, together with progress. Public commitments made in investor presentations and annual reviews now sit within a statutory reporting framework.
Parliament has provided a modified liability regime for statements about Scope 3 emissions, scenario analysis and transition plans in reports for financial years beginning between 1 January 2025 and 31 December 2027. During this period, only ASIC may bring proceedings in respect of those statements, and only in limited circumstances. This is a transitional protection, not a licence for imprecision. It expires, and the disclosures made under it will form the baseline against which later reports are compared.
The assurance phase-in under AASB S2
Assurance is where preparedness is most often underestimated. Under the AUASB's ASSA 5010, assurance is phased in alongside reporting and conducted by the entity's financial statement auditor. In the first year, limited assurance applies to Scope 1 and 2 emissions and to specified governance and strategy disclosures. The scope then widens progressively, extending to Scope 3, scenario analysis and transition planning, and moving towards reasonable assurance. For financial years beginning on or after 1 July 2030, reasonable assurance applies to all mandatory climate disclosures.
The implication is that climate data must be produced to an auditable standard from the outset. Limited assurance still requires documented methodologies, clear boundaries, evidence trails and controls over data collection. Entities that build their emissions inventory in spreadsheets maintained by a single individual will find the first assurance engagement uncomfortable and expensive. The disciplines familiar from financial reporting, including segregation of duties, reconciliation and management review, now apply to carbon.
Directors carry personal accountability. The sustainability report must include a directors' declaration. For the first three years, directors declare whether the entity has taken reasonable steps to ensure compliance. That standard rewards visible process: board minutes, committee oversight, documented judgements and a credible remediation plan for known gaps.
The wider context: why this is not an isolated compliance exercise
AASB S2 places Australia within a converging international baseline. Thailand's securities regulator has confirmed ISSB-aligned reporting from 2027, adding to the regional momentum behind the global standard. The ISSB is now consulting on nature-related disclosures, signalling where expectations will move next. Meanwhile, carbon border mechanisms in the EU and the planned UK CBAM from 2027 are already reshaping commercial terms for emissions-intensive exports, with analysts noting that the EU mechanism is likely to widen the premium for high-grade iron ore. For Australian resources and manufacturing businesses, emissions data reported under AASB S2 will increasingly be the same data that customers, lenders and trade authorities rely on. Consistency across these uses is a commercial matter as much as a regulatory one.
What to do before the first report
For entities approaching their first reporting period, priorities are clear. Confirm Group classification on a consolidated basis. Conduct a gap assessment against AASB S2 and ASIC Regulatory Guide 280. Establish board and committee oversight, with defined responsibilities. Build an emissions inventory with controls designed for assurance, and begin Scope 3 supplier engagement now. Run a dry-run report, ideally with a readiness review by the assurance provider, at least one cycle before the mandatory year.
CorpStage works with boards and reporting teams across this sequence, from Group assessment and scenario analysis through to data governance and assurance readiness. Our view is that the first AASB S2 report sets the reference point for every report that follows, and that it deserves the same rigour as the financial statements beside it.