Australia's Climate Reporting Timeline: 2025, 2026 and 2027 Explained
A clear summary of when mandatory climate reporting starts for each group of Australian entities, what's required in each phase, and how assurance requirements tighten over time.
Walid Hajj
Co-founder, Ayika Labs
Australia’s mandatory climate reporting regime is rolling out in three phases. Understanding the timeline — and what each phase requires — is the starting point for any organisation assessing its readiness obligations.
The three-group structure
The Corporations Act now requires sustainability reporting from entities that meet size thresholds, organised into three groups. Reporting begins at different times for each group, and the assurance requirements ramp up over time within each group.
Group 1 — From FY2025
Start date: Financial years beginning on or after 1 January 2025
Who qualifies (two of three):
- Consolidated revenue > $500 million
- Consolidated gross assets > $1 billion
- More than 500 employees
Group 1 companies are already in the first year of mandatory reporting. Their first sustainability reports — covering governance, strategy, risk management, Scope 1 and Scope 2 emissions — are due alongside their annual reports for FY2025.
Assurance for Group 1 starts at limited assurance, transitioning to reasonable assurance in later years as the assurance standards mature and capacity builds in the market.
Group 2 — From FY2026
Start date: Financial years beginning on or after 1 July 2026
Who qualifies (two of three):
- Consolidated revenue > $200 million
- Consolidated gross assets > $500 million
- More than 250 employees
Group 2 includes a large number of mid-to-large Australian companies across construction, manufacturing, retail, professional services, and infrastructure. For a company with a July financial year start, the first reporting period begins in July 2026 — meaning first reports will be lodged in late 2027 or early 2028.
For a company with a December or January financial year, the first reporting period starts January 2027.
Group 3 — From FY2027
Start date: Financial years beginning on or after 1 July 2027
Who qualifies (two of three):
- Consolidated revenue > $50 million
- Consolidated gross assets > $25 million
- More than 100 employees
Group 3 captures a broad range of smaller reporting entities. The obligations are the same as Groups 1 and 2 in substance, but Group 3 has slightly more transition relief (for example, additional time before Scope 3 emissions must be included).
What’s phased in over time
Not everything is required from day one. The AASB has built in transition relief on several items:
| Requirement | Group 1 | Group 2 | Group 3 |
|---|---|---|---|
| Scope 1 & 2 emissions | Year 1 | Year 1 | Year 1 |
| Scope 3 emissions | Year 2 | Year 2 | Year 3 |
| Prior period comparatives | Year 2 | Year 2 | Year 2 |
| Scenario analysis | Year 1 | Year 1 | Year 2 |
The phasing gives companies time to build capability, but the Scope 1 and 2 obligations and the governance/strategy disclosures are required from the first report.
How assurance requirements evolve
All three groups are subject to external assurance from year one, starting with limited assurance. The Auditing and Assurance Standards Board (AUASB) published ASSA 5000 (complete subject matter) and ASSA 5010 as the sustainability assurance standards.
Limited assurance requires the assurance practitioner to perform sufficient procedures to conclude that nothing came to their attention indicating the information is materially misstated. In practice, this means reviewing the methodology and testing a sample of underlying data.
Reasonable assurance — a higher standard closer to a financial audit — is expected to be phased in as the market develops capacity and organisations build more mature reporting processes.
What this means for preparation timing
Working backwards from reporting deadlines:
- A Group 2 company with FY starting July 2026 needs to have data collection processes in place from 1 July 2026 to capture the first reporting period
- Building those processes — mapping data sources, establishing collection workflows, selecting emission factors — takes several months at minimum
- Getting external assurance lined up typically requires starting conversations 6–9 months before the report is due
For most Group 2 companies, mid-2025 was the ideal time to start. If you’re reading this in 2026, there’s still time — but the work needs to start now.
Ayika helps Group 2 and Group 3 companies build the data infrastructure they need before their first reporting period starts. Book a demo to talk through your timeline.
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