Australia climate reporting rules: who must report under AASB S2

Australia's mandatory climate reporting regime is already operating. Group 1 financial years began on 1 January 2025, the first 259 reports have been lodged, and Group 2 periods began on 1 July 2026. The reporting duty depends on Australian statutory thresholds and filing rules, not on whether a company simply describes itself as aligned with international standards.

For most reporting teams, the first question is not what AASB S2 contains. It is whether the entity is inside Chapter 2M of the Corporations Act and meets one of the climate-reporting thresholds for the financial year. Only then do the standard, filing timetable and assurance requirements become the working brief.

The phasing dates describe the start of a reporting period, not the day a report must be published. A Group 2 company with a 30 June year-end enters the regime for the year beginning 1 July 2026. Its first report follows after that year has ended, within the applicable statutory filing window.

Who must report under Australia's climate rules

Australian Securities and Investments Commission (ASIC) guidance divides reporting entities into three groups. A company using the corporate-size route must already prepare an annual financial report under Chapter 2M and meet at least two of the three tests for its group. Separate routes apply to certain National Greenhouse and Energy Reporting (NGER) entities and large asset owners.

The figures above are a screening tool, not a substitute for the legislation. Group structure, controlled entities, financial-reporting status and the precise statutory definitions can change the answer. Foreign companies registered in Australia are not automatically brought into the regime if they do not have the relevant Chapter 2M reporting obligation.

Group 3 also has a material climate-risk condition. An entity meeting the Group 3 size thresholds is required to prepare a sustainability report, but it may make a statement that it has no material climate-related financial risks or opportunities if that conclusion is supported by the required assessment. That is not the same as being outside the regime.

A reporting start date is not a filing deadline

The phasing dates attach to financial years. ASIC then applies the annual-report lodgement timetable after the reporting period ends. Disclosing entities generally have three months, while other reporting entities generally have four months.

For a Group 1 entity with a 31 December 2025 year-end, the first report was due by 31 March 2026 if it was a disclosing entity and by 30 April 2026 otherwise. For an in-scope entity with a 30 June 2026 year-end, the corresponding dates were 30 September and 31 October 2026.

Group 2 follows the same logic. A 30 June year-end entity entering on 1 July 2026 reports on the financial year ending 30 June 2027, then files within its applicable three or four-month window. The ESG reporting deadline tracker keeps reporting periods and publication deadlines separate for this reason.

AASB S2 is mandatory; AASB S1 is voluntary

The Australian Accounting Standards Board (AASB) issued two sustainability standards in September 2024. AASB S2 Climate-related Disclosures is the mandatory standard for entities captured by the Corporations Act. AASB S1, which covers general sustainability-related financial information, remains voluntary.

AASB S2 is based on International Financial Reporting Standard S2 (IFRS S2), developed by the International Sustainability Standards Board (ISSB), with changes for Australia's legal and institutional setting. It covers governance, strategy, risk management, climate resilience, metrics and targets, and Scope 1, Scope 2 and Scope 3 greenhouse gas emissions. Its Appendix D also supplies the general reporting requirements needed for climate information, so an entity applying AASB S2 does not have to apply AASB S1.

This makes Australia a climate-reporting regime rather than a mandatory sustainability-wide regime. A company can voluntarily publish broader information, but it should distinguish that material from the statutory AASB S2 report. Our guide to ISSB, IFRS S1 and IFRS S2 explains the international baseline behind the Australian standard.

The first 259 reports show where implementation is uneven

By 6 May 2026, 259 sustainability reports had been lodged with ASIC for financial years ending 31 December 2025. Thirty-four came from listed entities and 225 from unlisted entities. Mining, manufacturing, financial services, oil and gas, and electricity businesses were prominent among the early filers.

ASIC reviewed a subset rather than endorsing all 259 reports. Its early observations focused on whether readers could identify the mandatory climate information and understand it without voluntary material obscuring the statutory disclosures. Some reports added broader sustainability content without clearly separating it from AASB S2 information.

The filing count alone does not show whether the mandatory information is easy to find. A report can contain a large volume of climate language and still obscure the required disclosures. Clear boundaries, consistent cross-references and evidence connecting risks, scenarios, metrics and financial effects make the statutory report easier to follow.

Scope 3 receives first-year relief, not a permanent exemption

AASB S2 requires Scope 3 emissions, including financed-emissions information for relevant financial activities. In an entity's first annual reporting period, however, it can use transition relief and omit Scope 3. It can also continue that relief when presenting comparative information in the following period.

The relief changes the first filing, not the underlying data problem. Value-chain emissions usually depend on supplier information, estimates, emission factors and controls outside the reporting entity. Waiting until the second report to design the collection process leaves little room to test boundaries or explain changes in method.

Australia has also amended AASB S2 for periods beginning on or after 1 January 2027, with early application permitted. Those amendments clarify parts of greenhouse gas and financed-emissions reporting. Teams should record which version of the standard they are applying rather than treating AASB S2 as a static document. The Scope 3 supplier data collection guide covers the evidence trail behind supplier requests and estimates.

Assurance expands in stages

The Australian Auditing and Assurance Standards Board (AUASB) has set the assurance path in ASSA 5010. The same four-stage pattern applies to each reporting group from its own first year, so there is no single assurance date that describes every entity.

For Group 1 entities whose first reporting period began between January and June 2025, the detailed transition has an extra wrinkle: the first-year provisions can cover two reporting periods before the broader second-year requirements apply. The exact assurance scope should therefore be checked against the entity's group and financial-year start.

Reasonable assurance is the end state, but the first report is already subject to selected assurance work. Data ownership, retained source files and review controls cannot sensibly wait until the fourth year. The limited versus reasonable assurance guide explains how the two engagement levels differ.

What reporting teams need to settle now

For Group 2, the reporting clock is running. The immediate work is to confirm the statutory boundary, identify the first period, and connect each disclosure to an owner and a source. Companies close to a threshold also need a process for acquisitions, disposals and workforce changes that could alter the group assessment.

The reporting boundary should match the related financial statements unless the law permits otherwise. That brings climate information into the same group structure as financial reporting, while the underlying data may still sit across facilities, procurement systems, risk registers and spreadsheets. Our guide to sustainability reporting controls explains how those records can be connected without creating a parallel reporting process that finance cannot reconcile.

Scenario analysis, transition plans and anticipated financial effects require judgement as well as data. The working papers should show which assumptions were used, who reviewed them and how uncertainty was described. ASIC's early observations suggest that clear presentation will matter alongside technical completeness.

The final preparation step is a filing map. The reporting period, board approval, assurance work, financial-report timetable and ASIC lodgement date need to fit together. A technically complete climate report that misses the annual-report process is still a reporting failure.

Australia's regime is now an operating system, not a future proposal

The first reports are public, Group 2 periods have begun and the assurance timetable is in force. The remaining challenge is not whether climate reporting will arrive. It is whether each entity has correctly identified its cohort and built a report that can be traced from statutory scope to source evidence.

Check Chapter 2M first, test the applicable thresholds, identify the first financial year, then work backwards from the filing and assurance deadlines. “ISSB aligned” describes the technical ancestry. It does not provide the Australian compliance answer.

Sources

• Australian Treasury: climate-related financial reporting and guidance
• ASIC: who must prepare a sustainability report
• ASIC: how and when to lodge a sustainability report
• ASIC: early observations from the first sustainability reports
• AASB: AASB S2 Climate-related Disclosures
• AASB: Australian sustainability reporting standards
• AUASB: ASSA 5010 assurance timetable
• Feature image: Sydney City Business District by Hpeterswald, CC BY-SA 3.0