IFRS S1, IFRS S2 and AASB S2: what Australian boards and management need to know now
The new IFRS Sustainability Disclosure Standards are reshaping how Australian organisations communicate climate-related risks and opportunities. Here is what boards need to understand — and where the Australian rules diverge from the global baseline.
IFRS S1 and S2 are the global sustainability disclosure standards issued by the International Sustainability Standards Board (ISSB). In Australia, they are adopted as the Australian Sustainability Reporting Standards (ASRS): AASB S2, covering climate-related disclosures, is mandatory under the Corporations Act 2001, while AASB S1, covering broader sustainability topics, remains voluntary. Australian boards are therefore legally bound by AASB S2 — the local equivalent of IFRS S2 — not by the IFRS standards directly.
What IFRS S1 and S2 actually are
In June 2023, the ISSB issued its first two sustainability disclosure standards as a global baseline for capital markets.
- IFRS S1 — General Requirements for Disclosure of Sustainability-related Financial Information. The umbrella standard. It sets out how an entity identifies and discloses all sustainability-related risks and opportunities that could reasonably be expected to affect its cash flows, access to finance, or cost of capital.
- IFRS S2 — Climate-related Disclosures. The climate-specific standard, built on the four pillars of the former TCFD framework: Governance, Strategy, Risk Management, and Metrics & Targets.
Internationally, the two are designed to be applied together — S1 establishing the foundation and S2 providing the detailed climate requirements. The combined goal is a single, comparable language for sustainability information that investors and lenders can rely on across markets.
How Australia adopted them — the "climate-first" approach
This is where boards most often get caught out. Australia did not adopt IFRS S1 and S2 wholesale. The Australian Accounting Standards Board (AASB) took a deliberate climate-first approach, issuing two local standards in September 2024:
- AASB S2 — Climate-related Disclosures. Mandatory for in-scope entities under the Corporations Act 2001. It incorporates the parts of IFRS S1 needed to function as a standalone climate standard, so a company can meet its legal obligation by applying AASB S2 alone.
- AASB S1 — General Requirements for Disclosure of Sustainability-related Financial Information. Voluntary. Entities may elect to report on sustainability topics beyond climate, but they are not required to.
In short: globally, sustainability disclosure means IFRS S1 and S2. In Australia, the law currently only compels the climate piece — AASB S2 is the only mandatory Australian Sustainability Reporting Standard at this stage.
Why the distinction matters for your board right now
Three practical consequences flow from this for directors:
1. Your legal obligation has a specific name — and it is AASB S2.
Commentary, investor questions and global guidance will reference 'IFRS S2' or 'ISSB standards.' Your statutory duty is to comply with AASB S2 as embedded in the Corporations Act. The standards are interoperable, so an AASB S2 report can generally satisfy IFRS S2 expectations — important if you have international investors or cross-listed securities — but the compliance trigger is the Australian standard.
2. Climate disclosures now carry the same legal weight as financial statements.
Because AASB S2 is enacted through the Corporations Act, climate-related statements sit within the same regime of director duties, oversight and enforcement as your financial reports. They are not a marketing document or a CSR appendix — they are a regulated disclosure for which directors are accountable.
3. The voluntary/mandatory line will move.
AASB S1 is voluntary today. Investor and lender expectations for broader sustainability disclosure are already running ahead of the law, and the regulatory direction of travel is clear. Boards that build their climate reporting on infrastructure capable of extending to wider sustainability topics will be better positioned than those treating AASB S2 as a one-off compliance task.
What AASB S2 requires, and when it applies
AASB S2 organises disclosure around the same four pillars as IFRS S2 — Governance, Strategy, Risk Management, and Metrics & Targets — and applies on a phased timeline based on entity size:
- Group 1 — reporting periods beginning on or after 1 January 2025 (largest entities). These companies are already in their first reporting period.
- Group 2 — reporting periods beginning on or after 1 July 2026. For Group 2, this is now the most pressing deadline.
- Group 3 — reporting periods beginning on or after 1 July 2027 (smallest in-scope entities).
Key features boards should be briefed on:
- Scope 1 and 2 emissions are required from Year 1; Scope 3 becomes mandatory from Year 2, with data collection expected to start immediately.
- Climate scenario analysis must use at least two scenarios — one consistent with limiting warming to 1.5°C, and at least one higher-warming pathway exceeding 2°C.
- Limited assurance applies over Scope 1 and 2 emissions and certain disclosures from Year 1, escalating toward reasonable assurance over all climate disclosures by 2030.
- A modified liability period runs for three years from 1 January 2025, under which forward-looking disclosures — Scope 3, scenario analysis and transition plans — attract regulator-only enforcement. This is a transitional cushion, not an exemption.
The December 2025 alignment update
In December 2025, the AASB updated AASB S2 to align with the ISSB's December 2025 amendments to IFRS S2, easing certain implementation challenges and keeping the Australian standard interoperable with the global baseline. For boards, the takeaway is that AASB S2 is a living standard that tracks ISSB developments — reporting frameworks and methodologies (including how greenhouse gas emissions are measured under the GHG Protocol) should be reviewed each cycle rather than set and forgotten.
What boards should be doing now
A focused agenda for the next board cycle:
- Confirm your group and your first reporting period. Classification depends on consolidated revenue, assets and employee thresholds, and the first period aligns with your financial year. Get this in writing.
- Establish formal board oversight. AASB S2 expects identifiable governance — who on the board is accountable for climate disclosures, and through what process. Document it.
- Test your data readiness. Most organisations underestimate Scope 3. Begin value-chain data collection now, even where a grace period applies.
- Commission scenario analysis early. The methodology and assumptions must be defensible from Year 1, even where the forward-looking disclosures sit inside the modified liability window.
- Prepare for assurance. Limited assurance from Year 1 means your emissions data needs documented methodologies, reliable sources and an audit trail — built in, not retrofitted.
- Treat it as financial reporting, because legally it is. Bring the same rigour, internal controls and director-level examination you apply to the financial statements.
How Lever Impact helps
Lever Impact is a chartered accounting firm that approaches sustainability reporting through a finance lens — not a compliance-only one. We help Australian boards and CFOs translate IFRS S1 and S2 into their actual obligation under AASB S2, build assurance-ready disclosures, and connect climate reporting to capital strategy and enterprise value rather than leaving it as a standalone exercise.
If your board is preparing for its first AASB S2 reporting period — or wants to pressure-test work already underway — our sustainability reporting team can help.
Lever Impact Pty Ltd
Lever Impact Pty Ltd provides professional services including chartered accounting, corporate advisory, ESG transformation and sustainability advisory. Lever Impact Pty Ltd does not provide financial product advice or financial services.