ASRS Explained: AASB S1 vs S2, and What Each Requires

If you've started reading about Australia's climate reporting, you've hit an alphabet soup: ASRS, AASB S1, AASB S2. The short version is that ASRS is the regime, AASB S2 is the mandatory standard you report against, and AASB S1 is a separate, voluntary one. This guide walks through the difference in plain English, and what S2 asks of you.

ASRS, AASB S1, AASB S2: which is which

ASRS, the Australian Sustainability Reporting Standards, is the regime, phased in by company size (the plain-English guide to who's in and when is here). Within it sit two standards. AASB S2 covers climate-related disclosures, and it's the one the law makes mandatory. AASB S1 covers general sustainability-related financial information, which is broader than climate, and in Australia it's issued as a voluntary standard for entities that choose to disclose more widely. So when people say "ASRS S2" or "AASB S2," they mean the same thing: the mandatory climate standard. If you're preparing your first report, S2 is almost certainly your focus.

Both AASB standards are Australia's adoption of the global standards from the ISSB (the International Sustainability Standards Board), IFRS S1 and IFRS S2. In Australia you report against the AASB versions, not IFRS directly, but they're closely aligned by design, which helps if your group also reports overseas.

The ISSB issues IFRS S1 and IFRS S2; Australia adopts them as AASB S1 (voluntary) and AASB S2 (mandatory). — How the standards relate: the global ISSB standards, IFRS S1 and S2, adopted in Australia as AASB S1 (voluntary) and AASB S2 (mandatory).

What AASB S2 covers

A common misread is that AASB S2 is just an emissions calculation. In fact it spans four pillars: governance, strategy, risk management, and metrics and targets, and the emissions total is only the last of them. It covers Scope 1, 2 and 3, with first-year relief on Scope 3 to give value-chain data time to mature. For most first-time reporters the metrics pillar is the visible part, but the governance, strategy and risk disclosures are where most of the work sits.

AASB S2 is built on four pillars:

Governance

How the board and management oversee climate risks and opportunities.

Strategy

The climate risks and opportunities that affect your business, and your response.

Risk management

How you identify, assess and manage those risks.

Metrics and targets

Scope 1, 2 and 3 emissions and any targets, with Scope 3 relief in year one.

Why it's worth starting now

None of this is far off. ASIC Chair Joe Longo has called mandatory climate disclosure "the biggest changes to financial reporting and disclosure standards in a generation," and his advice to companies is to start now. Treasury's own impact analysis shows first-time compliance is a real commitment, much of it systems work and Scope 3 modelling. The report itself is one cycle, but the data foundations behind it take longer, which is why starting early matters: the first report is the hard one, and later years reuse the same foundations.

~$960k

First report

Treasury's estimate

4 FTE

Of effort

much of it systems and Scope 3

1,100 hrs

Year one

When it applies

ASRS is phased in by company size across three groups. Whether you're caught, and when, comes down to which group you fall into (who's in which group).

1 Jan 2025

Group 1

Largest entities, already reporting

1 Jul 2026

Group 2

Mid-to-large entities

1 Jul 2027

Group 3

Mid-market, first reports

“S2 is mandatory and about climate; S1 is voluntary and broader. For a first report, S2 is the one to focus on.”

The short version

Still mapping out AASB S2?

If you'd like a second read on where you stand, or to see what a first Scope 1, 2 and 3 inventory looks like on your own numbers, book a check-up. No obligation.

Book a Sustainability Check-up

Frequently asked questions

What is the difference between AASB S1 and AASB S2?+

AASB S2 is the climate-related disclosures standard, the one made mandatory under Australia's ASRS regime. AASB S1 sets out general requirements for disclosing broader sustainability-related financial information beyond climate, and in Australia it is issued as a voluntary standard for entities that choose to report more widely. In short: S2 is mandatory and climate-specific, S1 is voluntary and broader.

Is AASB S1 mandatory in Australia?+

No. The mandatory ASRS obligation is AASB S2, the climate standard. AASB S1 is available as a voluntary standard for organisations that want to make wider sustainability disclosures, but it is not what the phased ASRS mandate requires. Most first-time reporters focus on AASB S2.

Is "ASRS S2" the same as "AASB S2"?+

Yes. ASRS is the regime; AASB S2 is the standard within it. People say "ASRS S2" and "AASB S2" interchangeably to mean the mandatory climate-related disclosures standard you report against.

Is AASB S2 the same as IFRS S2 or the ISSB standard?+

AASB S2 is Australia's adoption of IFRS S2, the climate standard issued by the ISSB (the International Sustainability Standards Board). They're closely aligned but not identical, and in Australia you report against AASB S2. The alignment is deliberate, so a business with international operations can broadly reconcile its Australian disclosure with the global baseline instead of starting over.

What does AASB S2 actually require?+

Disclosure across four pillars: governance, strategy, risk management, and metrics and targets, plus your greenhouse gas emissions across Scope 1, 2 and 3. It isn't only an emissions number. Most of the effort for first-time reporters sits in structuring the governance, strategy and risk disclosures and in gathering defensible Scope 3 data, with first-year relief on Scope 3 to let that data mature.