Key Takeaways:
AASB S2 is Australia’s mandatory climate disclosure law, already in force for Group 1 companies from January 2025, with Groups 2 and 3 following in 2026 and 2027. In-scope businesses must report on climate-related risks and opportunities across governance, strategy, risk management, and Scope 1–3 emissions — submitted annually to ASIC.
Assurance requirements escalate over time, moving from limited to reasonable assurance by around 2030, which means the data infrastructure you build now will determine how painful that transition is. Companies that treat AASB S2 as a compliance checkbox rather than a reporting capability will pay for it — in rework costs, assurance failures, and increasingly, in how lenders and investors price their risk.
Mandatory climate reporting is live in Australia. The largest companies started disclosing for financial years from 1 January 2025. Mid-size and smaller entities are next, with deadlines landing in 2026 and 2027. If your company is in scope, or likely to be, here’s what the standard actually requires and where most businesses are currently underprepared.
What is the AASB?
The Australian Accounting Standards Board (AASB) is the government body that develops and maintains Australia’s financial and sustainability reporting standards, covering both private and public sector entities. It works alongside the Australian Auditing and Assurance Standards Board (AUASB), which handles assurance requirements for sustainability disclosures.
The AASB has aligned its sustainability standards with the International Sustainability Standards Board (ISSB), so Australian disclosures are comparable with what companies are reporting in the UK, Canada, and elsewhere. They have produced the ASRS framework (Australian Sustainability Reporting Standards), which currently has two standards: AASB S1 and AASB S2.
AASB S1 vs AASB S2
AASB S1 covers general sustainability-related financial disclosures. It’s voluntary and applies to entities that want to report on sustainability topics beyond climate — think biodiversity, water, social factors.
AASB S2 is the mandatory one. It’s specific to climate and is what most Australian businesses need to focus on right now.
Both are built on the IFRS S1 and S2 (international financial reporting standards) frameworks from the ISSB. The critical difference from the global versions: AASB S2 sits inside the Corporations Act 2001. That means non-compliance carries civil penalties for directors — this isn’t a reputational nudge, it’s law. AASB S2 also drops the industry-specific metrics in IFRS S2, which does simplify things somewhat for Australian reporters.
What AASB S2 Actually Requires
Covered entities must disclose how climate-related risks and opportunities could affect their cash flows, access to finance, and cost of capital — across short, medium, and long time horizons. The disclosures fall across four areas.
- Governance. How does the board oversee climate risks and opportunities? Who’s accountable when something changes?
- Strategy. How do climate factors affect the business model and financial plans? Companies have to show resilience under at least two climate scenarios, one of which must be aligned with limiting warming to 1.5°C. This is where the scenario analysis requirement lives, and it’s harder than it sounds.
- Risk management. How are climate risks identified and folded into existing enterprise risk processes?
- Metrics and targets. Scope 1 (direct emissions), Scope 2 (energy-related), and in many cases Scope 3 (value chain) must all be reported. Internal carbon prices, climate targets, and progress against them also need to be disclosed.
Everything goes into an annual sustainability report submitted to ASIC, alongside a directors’ declaration and climate statement notes.
Who Has to Comply — and When?
Three groups, phased in by size.
- Group 1 — large listed companies, major asset owners, financial institutions — started reporting for financial years from 1 January 2025.
- Group 2 enters the regime for periods starting 1 July 2026.
- Group 3 — typically mid-size companies — from 1 July 2027.
One thing worth flagging even if you’re not in scope yet: Scope 3 emissions reporting creates pressure up and down supply chains. When your large customers are required to disclose their value chain emissions, they’ll come asking for data from suppliers. That conversation is coming whether you’re directly covered or not.
Assurance: The Timeline That Catches Companies Off Guard
The AUASB introduced ASSA 5010, which phases in assurance requirements over time.
Year one: limited assurance on governance, strategy, and Scope 1 and 2 disclosures only. Years two and three: limited assurance across the full sustainability report. From around 2030 (year four): reasonable assurance — the same standard applied to financial statements.
That jump from limited to reasonable assurance is where companies get caught out. Reasonable assurance demands a level of internal control, documentation, and data integrity that doesn’t materialise overnight. The early years of limited assurance aren’t a grace period so much as the window you have to build something that will actually hold up. Companies treating year one as a dress rehearsal are setting themselves up for a difficult transition.
Five Steps to Get Ready
Know your group. Check your consolidated revenue, assets, and employee count. Work backwards from your reporting deadline and map what needs to be in place by when.
Do a climate risk assessment. Physical risks (flooding, heat stress, drought) and transition risks (carbon pricing, policy shifts, market changes) need to be identified across your operations, supply chain, and customer base. The assessment should look at materiality from both a financial and operational angle.
Take scenario analysis seriously. Most businesses underestimate this one. You need to model exposure under at least two climate futures — one aligned with Paris pathways, one reflecting higher warming. That means documented assumptions, quantitative and qualitative analysis, and real input from finance, risk, and strategy teams. It’s not a desk exercise.
Get your emissions baseline right. Build or tighten your Scope 1 and 2 GHG inventory now. Start mapping Scope 3 categories relevant to your sector — Group 1 entities need Scope 3 from their second reporting year.
Sort out governance before you need it. Assign ownership of climate disclosures at board and management level. Set up internal review and sign-off processes. AASB S2 gives boards a three-year modified liability window, but that’s not a substitute for doing things properly.
The Data Problem Nobody Talks About Enough
Most AASB S2 guides spend a lot of time on what to disclose. The harder, less-discussed problem is the quality of the data sitting behind those disclosures.
Scope 1 and 2 data is already messy for most organisations — inconsistent metering, gaps across sites, invoicing data in a dozen different formats. Scope 3 is a different scale of difficulty. The data lives across suppliers, logistics partners, and customer interactions. It arrives as ERP exports, spreadsheets, PDFs, and sometimes nothing at all.
Assurance providers don’t just check the numbers in the sustainability report. They check the process that produced them — how emissions were calculated, what assumptions were used, whether the methodology is documented and reproducible. An audit trail matters as much as the figure at the end.
This is where manual, spreadsheet-based approaches start to break down. They might get you through year one under limited assurance. They won’t hold up when reasonable assurance arrives, and rebuilding everything mid-program is expensive.
What Happens if You Don’t Comply?
Penalties for non-compliance mirror financial reporting failures under the Corporations Act, which means civil penalties for directors. ASIC has signalled some flexibility during the transition, but that flexibility applies to entities making genuine attempts to comply — not to ones that haven’t started.
The more immediate concern for many companies isn’t the regulator. It’s the investor. Climate disclosures are increasingly used by lenders and capital markets to assess risk. Companies that can’t produce credible, auditable climate data will find that reflected in their financing conversations before ASIC gets involved.
Where to Start
The groundwork is the same regardless of which group you’re in: clear governance, a solid emissions baseline, scenario analysis capability, and data infrastructure that can support the assurance process.
Climate reporting in Australia is not going away, and it’s not getting simpler. The companies that build real capability now — rather than assembling a disclosure at the last minute — will find the ongoing cost of compliance much lower, and the insights genuinely useful.
CrediblESG supports Australian businesses through AASB S2 compliance, from emissions data management to ASRS-aligned sustainability reporting. Get in touch to see where your current gaps are.
Frequently Asked Questions
What is the AASB S2?
AASB S2 is Australia’s mandatory climate disclosure law — not a guideline, not a best-practice framework, an actual legal requirement. Companies in scope have to report on how climate-related risks and opportunities could affect their cash flows, financing costs, and access to capital. That covers governance, strategy, risk management, and emissions numbers across Scope 1, 2, and eventually 3. The Australian Accounting Standards Board issued it as part of the broader Australian Sustainability Reporting Standards. Group 1 entities — the largest listed companies and financial institutions — started reporting for financial years from 1 January 2025. Groups 2 and 3 follow in 2026 and 2027.
What is the difference between IFRS S2 and AASB S2?
AASB S2 is built on IFRS S2 — the global climate disclosure standard from the International Sustainability Standards Board — but localised for Australia. The core requirements are largely the same: disclose climate risks and opportunities, run scenario analysis, report Scope 1–3 emissions. Where things diverge is legal force and local adjustments. IFRS S2 is voluntary internationally. AASB S2 sits inside the Corporations Act 2001, which means non-compliance carries civil penalties for directors. Australia also stripped out the industry-specific metrics that IFRS S2 includes and replaced the standard’s reporting period references with its own phased group timeline.
What is S1 and S2 in accounting?
Under Australia’s sustainability reporting framework, S1 and S2 are shorthand for the two standards that make up the ASRS. AASB S1 sets the general principles for disclosing any sustainability topic that could affect financial position — think biodiversity, water, social impacts. It’s currently voluntary. AASB S2 zooms in specifically on climate and is mandatory. The pair mirrors the IFRS S1 and S2 standards from the ISSB, adapted for Australian law. In practice, most companies are focused on S2 right now because that’s where the compliance deadlines are.
What is the AASB S2 amendment?
The amendment refers to the changes introduced by the Treasury Laws Amendment (Financial Market Infrastructure and Other Measures) Act 2024, which formalised mandatory climate reporting under the Corporations Act. It set up the three-group structure with staggered deadlines from 2025 to 2027, introduced the phased assurance requirements through ASSA 5010, and created some transitional relief — including the option to defer Scope 3 emissions reporting in year one. Worth knowing: that deferral doesn’t roll forward indefinitely. Full Scope 1, 2, and 3 reporting is expected from the second reporting year for most covered entities, so companies that treat year one as a free pass on Scope 3 data collection will feel it later.
