AASB S1 vs S2: What’s the Difference and Which Do You Need?

Australia issued two sustainability reporting standards together in September 2024. AASB S2 Climate-related Disclosures is mandatory for entities captured by the Treasury Laws Amendment (Financial Market Infrastructure and Other Measures) Act 2024. AASB S1 General Requirements for Disclosure of Sustainability-related Financial Information is voluntary.

The split is a deliberate Australian design. The IFRS Foundation issued IFRS S1 and IFRS S2 as a paired set, both designed to apply together, leaving each jurisdiction to decide whether each is mandatory. Australia adopted IFRS S2 with four modifications and made it mandatory; AASB S1 was adopted without modification and made voluntary. AASB S2 was built to function as a standalone standard so the voluntary status of AASB S1 doesn’t leave a compliance gap.

The short answer for most AASB S2 reporters: you do not need AASB S1. Your disclosure mechanics sit inside Appendix D of AASB S2.

The Australian Government decision: climate first, the rest later

The policy reason for the split is in BC14(a), the Basis for Conclusions paragraph explaining the AASB’s decision to issue two standards.

the voluntary Standard AASB S1 General Requirements for Disclosure of Sustainability-related Financial Information, to incorporate all IFRS S1 requirements without modification. Consistent with the Australian Government’s decision to address climate-related financial disclosures first and to consider the development of reporting requirements for other sustainability-related risks and opportunities in Australia over time, the AASB decided to issue AASB S1 as a voluntary Standard so that an entity applying AASB S2 is not required to apply AASB S1 to disclose information on other sustainability-related risks and opportunities

(AASB S2 BC14(a), page 48)

The policy direction is climate first, set by the Treasury Policy Position Statement Mandatory climate-related financial disclosures (January 2024). The AASB followed.

The standard repeats this reasoning one paragraph later, in BC18:

IFRS S1 sets out the general requirements for a complete set of sustainability-related financial disclosures. IFRS S1 is designed to be applied in conjunction with IFRS S2, which is a topic-based Standard that specifies disclosures relating to climate. As noted in paragraph BC14(a), consistent with the Australian Government’s decision to address climate-related financial disclosures first and to consider the development of reporting requirements for other sustainability-related risks and opportunities in Australia over time, the AASB decided to issue AASB S1 as a voluntary Standard…

(AASB S2 BC18, page 49)

Plain-language reading: the IFRS Foundation designed S1 and S2 to work together. AASB S1 carries the general disclosure mechanics; AASB S2 carries the climate-specific content. The Australian Government decided not to mandate the general layer yet.

That left the AASB with two choices: issue AASB S2 as mandatory and tell reporters to also voluntarily apply IFRS S1 mechanics, or issue AASB S2 as a standalone mandatory standard that contains everything an entity needs to comply. The AASB chose the second option. Appendix D makes that work.

The AASB also issued AASB S1 as voluntary for the same time period. Reporters who want to extend their disclosure to non-climate sustainability matters (nature, biodiversity, social) now have a standard Australian framework rather than ad hoc disclosure.

For a climate reporter, the two-standard issuance is a policy artefact, not a compliance burden. The default position is to apply AASB S2 only.

What AASB S1 contains, in plain terms

AASB S1 is IFRS S1 word for word, with no Australian modifications. BC14(a) says so explicitly: “to incorporate all IFRS S1 requirements without modification.”

What IFRS S1 covers, and therefore what AASB S1 covers:

• Disclosure mechanics for the full set of sustainability-related risks and opportunities. Climate is one topic inside that set, not the whole set
• Materiality: the test that decides what gets disclosed and what does not
• Fair presentation: the requirement for disclosures to faithfully represent what they describe
• Comparatives: prior-period information for amounts disclosed in the current period
• Statement of compliance: how an entity claims compliance with the standard
• Sources of guidance: what an entity can refer to when applying the standard
• Judgements, uncertainties, and errors: how an entity discloses the judgement calls it made
• Location of disclosures: where in the general purpose financial report sustainability information lives

The scope is broad. “All sustainability-related risks and opportunities” includes climate. It also includes nature and biodiversity, social and human capital, governance, and any other sustainability matter that could reasonably be expected to affect the entity’s prospects. AASB S1 does not name the topics. It governs the disclosure architecture, and topic selection is left to materiality.

A reporter voluntarily applying AASB S1 commits to that full architecture for whatever topic scope they choose.

For paragraph-level detail on IFRS S1’s content, see our IFRS S1 and S2 overview at https://continuuiti.com/blog/ifrs-s1-and-s2/.

For a climate reporter: if your disclosure target is climate only, Appendix D of AASB S2 supplies every mechanic you need. Voluntary AASB S1 is the path only if you want to extend beyond climate.

What AASB S2 contains, briefly

AASB S2 is IFRS S2 with four modifications. The AASB itself enumerates them in BC14(b). Our earlier piece walks the four modifications in detail at https://continuuiti.com/blog/aasb-s2-vs-ifrs-s2-physical-risk/.

Brief recap:

• Modification 1: Appendix D. This appendix supplies the IFRS-S1-equivalent disclosure mechanics, scoped to climate.
• Modification 2: consolidated reporting. A new paragraph (Aus20.1) lets a parent entity choose to disclose for the parent-only entity rather than the consolidated group, per section 292A(2) of the Corporations Act 2001.
• Modification 3: industry-based information. The IFRS S2 requirements to use SASB-style industry topics and metrics (paragraphs 12, 23, 28(b), 32, 37, B65(d), and B67) are modified or omitted, as an interim measure until AASB finalises Australian industry-based disclosures by 2030. Our earlier piece walks the precise mix of pure deletions, IBG-stripping replacements, and the effective-date paragraph.
• Modification 4: not-for-profit users. AU-specific user definitions for not-for-profit entities are added in paragraphs AusA1, AusB14.1, and AusB15.1.

For a physical-risk-disclosure reporter, the load-bearing paragraphs are unchanged from IFRS S2. Para 22 (scenario analysis), Para 25 (anticipated financial effects of climate-related risks and opportunities), Para 29(c) (the amount and percentage of assets vulnerable to climate-related physical risks), Para 29(e) (capital deployment toward climate-related risks and opportunities), Appendix B paragraphs B1 through B18 (scenario-analysis methodology), and B64 through B65 (cross-industry-metrics application guidance) all carry their IFRS S2 wording verbatim.

Platforms like Continuuiti provide the physical-risk data layer for AASB S2’s load-bearing paragraphs: 12-hazard assessment under SSP scenarios that satisfies the Para 22 scenario-analysis requirement, with damage estimates that quantify the Para 29(c) asset-vulnerability metric.

Why AASB S2 has its own Appendix D

The structural reason is in BC20:

Since AASB S1 is a voluntary Standard, the AASB included Appendix D General Requirements for Disclosure of Climate-related Financial Information in AASB S2 to incorporate the content of IFRS S1 necessary to enable AASB S2 to function as the standalone mandatory Standard containing all of the requirements regarding climate-related disclosures. Consequently, where IFRS S2 cross-references to IFRS S1 paragraphs, AASB S2 cross-references to Appendix D paragraphs. Accordingly, AASB S2 contains all the requirements an entity would need to apply in reporting climate-related financial disclosures in accordance with AASB S2.

(AASB S2 BC20, page 49)

Plain-language reading: AASB S1 is voluntary. The AASB cannot assume an AASB S2 reporter also applies AASB S1. So AASB S2 has to be standalone, and the IFRS-S1-equivalent disclosure mechanics had to go inside AASB S2 itself. Appendix D is where they went.

The selection rule for what content went into Appendix D is in BC21, which describes the three-question test the AASB applied:

In assessing the contents of IFRS S1 needed to make AASB S2 function as intended, the AASB considered whether:
(a) an IFRS S1 principle, disclosure or guidance is already incorporated in AASB S2;
(b) an IFRS S1 principle reflects content already in the AASB’s Conceptual Framework for Financial Reporting (in respect to for-profit entities) and the Framework for the Preparation and Presentation of Financial Statements (in respect to not-for-profit entities) that are available as support material for applying AASB S2, including considering the extent to which that content is the same; and
(c) the IFRS S1 content reflects corresponding content in Accounting Standards, i.e. material considered necessary to include in Accounting Standards to enable them to function.

(AASB S2 BC21, page 49)

Plain-language reading: if the content was already covered in any of the three buckets (in AASB S2 itself, in the AASB Conceptual Framework, or in existing Accounting Standards), the paragraph did not need to be repeated in Appendix D. The IFRS S1 content that did land in Appendix D is the content that fit none of the three buckets.

There was a sub-debate about whether to include the conceptual content from IFRS S1 in Appendix D. The original Exposure Draft (ED SR1) proposed not to include it, on the basis that the AASB Conceptual Framework is not a legislative instrument and therefore not enforceable as part of accounting standards (BC22). Stakeholders pushed back. BC23 records their argument: sustainability reporting is a new context, and conceptual scaffolding helps preparers ensure their reported climate information is relevant to users and faithfully represents the underlying substance. The AASB re-evaluated and changed position, as BC24 records:

Accordingly, the AASB concluded it would include the conceptual content in IFRS S1 in Appendix D in AASB S2, together with the other general principles in IFRS S1 that are considered necessary to enable AASB S2 to function as intended.

(AASB S2 BC24, page 50)

One practical detail completes the design. Every IFRS S2 cross-reference to an IFRS S1 paragraph maps to the corresponding Appendix D paragraph in AASB S2. The AASB kept the IFRS S1 numbering in Appendix D so reporters who voluntarily apply both standards can cross-walk cleanly (Appendix D preamble paragraph 4, page 31).

What is NOT in Appendix D

The Appendix D preamble paragraph 4 names a discipline: “the paragraphs of AASB S1 that are not included in this appendix are noted.” The AASB followed through. Throughout Appendix D, paragraphs that were not transposed from AASB S1 are explicitly tagged [Not included]. That tag is itself the map of what an AASB-S2-only reporter does not have, and what a voluntary-AASB-S1 reporter does have.

The AASB tagged 16 paragraph ranges as [Not included] in Appendix D. 14 are pure omissions, paragraphs left out because they were either already covered elsewhere (per the BC21 test) or because their content is scoped to sustainability matters beyond climate. 2 are substitutions, IFRS S1 paragraphs replaced by AU-specific paragraphs covered as Modification 2 in our earlier piece on AASB S2 vs IFRS S2.

The omissions, in document order:

The Appendix D preamble paragraph 6 names exactly three change types the AASB made when transposing AASB S1 paragraphs into Appendix D: scope limited to climate, AU pronouncement references replace international references, and cross-references to paragraphs not included in Appendix D are removed. The substantive content of every transposed paragraph is unchanged.

For a climate reporter, the omissions are not gaps in your compliance. They are paragraphs scoped to sustainability disclosure beyond climate.

When voluntary AASB S1 makes sense

A reporter applying AASB S2 has the choice to also voluntarily apply AASB S1. The Appendix D preamble paragraph 5 names the option:

An entity applying AASB S2 is not required to apply AASB S1. Rather, an entity applying AASB S2 is required to comply only with AASB S2, including this appendix. The entity does not need to consider AASB S1 or the paragraphs of AASB S1 that are not included in this appendix. However, the entity may refer to AASB S1 for guidance in complying with the requirements in this appendix.

(AASB S2 Appendix D preamble, paragraph 5, page 31)

If a reporter elects voluntary AASB S1 application, two integration paragraphs in the body of AASB S2 apply: Aus7.1 (the AU-specific governance paragraph) and Aus26.1 (the AU-specific risk management paragraph). Both were added by the AASB for the voluntary-AASB-S1-alongside scenario. BC19 explains why:

Consequently, the AASB added paragraphs Aus7.1 and Aus26.1 to clarify that the requirements set out in IFRS S2 paragraphs 7 and 26 apply particularly if an entity elects to also apply AASB S1 to disclose information about other sustainability-related risks and opportunities in addition to climate-related risks and opportunities in GPFR. The paragraphs require an entity to avoid unnecessary duplication of disclosures by providing integrated disclosures instead of separate disclosures for each sustainability-related risk and opportunity, if oversight of sustainability-related risks and opportunities is managed on an integrated basis.

(AASB S2 BC19, page 49)

Plain-language reading: if you apply both standards and your governance or risk management operates on an integrated basis across climate, nature, social, and other sustainability matters, you must provide integrated disclosures rather than duplicating per topic. The rule prevents a reporter from publishing a climate governance section, a nature governance section, and a social governance section that all describe the same committee meetings, the same risk-register process, and the same board mandate.

When voluntary AASB S1 makes sense:

• The reporter intends to disclose nature, biodiversity, social, or other non-climate sustainability matters under a standard Australian framework, and prefers AASB S1 architecture to building from scratch.
• The reporter is preparing for the broader sustainability disclosure direction signalled by BC14(a) and BC18 (the Australian Government policy to consider broader sustainability requirements over time) and wants to build the disclosure muscle now rather than at future mandate.
• The reporter is multi-regime. For example, an ASX-listed entity that also reports under the European Sustainability Reporting Standards (a multi-topic mandatory-paired sustainability regime in the EU covering climate, pollution, water, biodiversity, circular economy, and social topics) or a global IFRS S1 + S2 framework. Voluntary AASB S1 application gives Australian-side consistency.

When voluntary AASB S1 does not make sense:

• The reporter’s disclosure target is climate only. Appendix D supplies the disclosure mechanics. AASB S1 adds nothing the reporter needs.
• The reporter’s risk-management focus is physical climate risk. The load-bearing paragraphs (Para 22, Para 25, Para 29(c), Para 29(e), Appendix B B1 through B18, and B64 through B65) are unchanged from IFRS S2 and sit in the body and appendices of AASB S2.
• The reporter wants to minimise assurance scope and auditor questions. Voluntary AASB S1 application expands the assurance perimeter to the broader sustainability disclosures, with downstream implications for the audit attestation framework.

Voluntary AASB S1 is a strategic choice driven by disclosure ambition, not a compliance requirement. The trigger for opt-in should be a decision to extend disclosure scope beyond climate, not a feeling that AASB S2 on its own is incomplete. AASB S2 on its own is complete for climate disclosure.

What if AASB S1 became mandatory in Australia?

The Treasury Policy Position Statement Mandatory climate-related financial disclosures (January 2024) signalled the climate-first sequencing and contemplated broader sustainability requirements “over time.” No timeline. No specific scope.

Whether broader sustainability disclosure becomes mandatory in Australia, and when, is a Treasury and Parliament decision. The standard-setting infrastructure is already in place: AASB S1 is issued and operative as voluntary. A future legislative mandate would be the missing piece.

For an AASB S2 reporter today, this is what would change if AASB S1 became mandatory:

• Disclosure mechanics: nothing. Appendix D already supplies the IFRS-S1-equivalent mechanics for climate. The same mechanics would apply to other sustainability topics.
• Disclosure scope: extends to non-climate sustainability matters that are material. The reporter would need to identify which non-climate matters meet the materiality threshold and disclose them under the AASB S1 architecture.
• Integration: mandatory rather than conditional. Aus7.1 and Aus26.1, currently scoped to the voluntary-application scenario, would apply to all reporters. Integrated governance and risk-management disclosures would become a default rather than a choice.
• Assurance perimeter: expands. The Australian sustainability assurance standard, ASSA 5000 General Requirements for Sustainability Assurance Engagements (the standard in force for AASB S2 limited assurance per the cohort-review evidence), would scope to the broader sustainability disclosures.
• Industry-based metrics: a separate workstream. The AASB has signalled in BC30 its intention to finalise mandatory industry-based disclosure requirements by 2030. That workstream sits beside the AASB S1 mandatory-adoption question, but the two would interact.

For a climate reporter today, nothing changes. The architecture is designed so that the transition, if it comes, is additive rather than disruptive. Reporters who have built strong AASB S2 capability, particularly on the materiality, judgement-and-uncertainty, and governance-integration mechanics, will find voluntary or future-mandatory AASB S1 application a scope extension. Not a redesign.

Key takeaways if you’re planning to disclose under AASB S2

If you are preparing an AASB S2 disclosure right now:

1. You do not need AASB S1 for AASB S2 compliance. Appendix D of AASB S2 contains every disclosure mechanic an AASB S2 reporter needs. The Appendix D preamble says so explicitly. BC20 explains why.

2. Your disclosure mechanics sit in Appendix D, not in AASB S1. When you cite materiality, you cite D-Para 14 and D-Para 17 (not IFRS S1 paragraph 14). When you cite fair presentation, you cite D-Para 11 through D-Para 16. When you cite judgements, you cite D-Para 74 and onwards. When you cite statement of compliance, you cite D-Para 72.

3. If you want to disclose nature, biodiversity, social, or other non-climate sustainability matters under a standard Australian framework, voluntary AASB S1 is the path. AASB S1 is IFRS S1 word for word, with no AU modifications.

4. If you apply both standards, integrate. Aus7.1 and Aus26.1 require integrated disclosures rather than duplicating per topic when oversight is managed on an integrated basis.

5. For physical-risk reporters specifically. Para 22, Para 25, Para 29(c), Para 29(e), Appendix B B1 through B18, and B64 through B65 (the load-bearing physical-risk paragraphs) are unchanged from IFRS S2 and sit in the body and appendices of AASB S2. Your AASB S2 work transfers cleanly to IFRS S2 jurisdictions and back.

Frequently asked questions

Do I need AASB S1 to comply with AASB S2?

No. Appendix D of AASB S2 contains every disclosure mechanic an AASB S2 reporter needs. The Appendix D preamble paragraph 5 says so explicitly: “An entity applying AASB S2 is not required to apply AASB S1.”

What is the difference between AASB S1 and AASB S2?

AASB S2 is mandatory and covers climate-related financial disclosures. AASB S1 is voluntary and covers the general requirements for disclosure of sustainability-related financial information, of which climate is one topic.

Why did Australia issue two standards on the same day?

Australian Government policy was to address climate first and consider broader sustainability requirements over time. The AASB followed that policy by issuing AASB S2 as mandatory and AASB S1 as voluntary, both in September 2024.

Should my company voluntarily apply AASB S1?

Only if you intend to disclose non-climate sustainability matters (nature, biodiversity, social) under a standard Australian framework. If your disclosure target is climate only, AASB S2 alone is complete.

Is AASB S1 mandatory in Australia?

No. AASB S1 is voluntary in Australia. It was issued by the AASB in September 2024 alongside the mandatory AASB S2, but the Australian Government’s policy is to address climate disclosure first and consider broader sustainability requirements over time. There is no announced timeline for AASB S1 becoming mandatory; any change would require a Treasury and Parliament decision.

What is AASB S1?

AASB S1 (General Requirements for Disclosure of Sustainability-related Financial Information) is Australia’s voluntary sustainability disclosure standard, issued September 2024. It is IFRS S1 word for word, with no Australian modifications. AASB S1 governs the disclosure architecture for all sustainability topics, including climate, nature, biodiversity, social, and governance, rather than naming specific topics. An entity voluntarily applying AASB S1 commits to that full architecture for whatever topic scope it chooses to disclose.

Sources

Standard text (AASB S2 Climate-related Disclosures, September 2024 issuance):

• Body paragraphs 1-9 (objective, scope, governance objective), Aus7.1 and Aus26.1 (voluntary AASB S1 integration)
• Appendix D paragraphs 10 through 86 (the general requirements baked in from AASB S1)
• Appendix D preamble paragraphs 1 through 6 (page 31)
• D-Para 14 and D-Para 17 (materiality), D-Para 72 (statement of compliance)
• Aus20.1 and AusB38.1 (the AU-specific consolidated reporting paragraphs)

Basis for Conclusions:

• BC14 (the two-standard decision), BC18 (voluntary S1 reasoning), BC19 (Aus7.1 and Aus26.1 integration rule), BC20 (standalone-mandatory architecture), BC21 (three-question selection test), BC22-BC25 (conceptual-content debate and final design), BC30 (industry-based 2030 target). Pages 48-51 of the standard.

Companion pieces:

• AASB S2 vs IFRS S2 from a physical-risk reporter’s perspective: https://continuuiti.com/blog/aasb-s2-vs-ifrs-s2-physical-risk/
• IFRS S1 and S2 overview: https://continuuiti.com/blog/ifrs-s1-and-s2/
• IFRS S2 paragraph 29(c), what it actually requires: https://continuuiti.com/blog/ifrs-s2-paragraph-29c-physical-risk/
• IFRS S2 first-wave disclosures: https://continuuiti.com/blog/ifrs-s2-first-wave-disclosures-skipped/
• AASB S2: Australia’s mandatory climate disclosure standard (overview): https://continuuiti.com/blog/aasb-s2/
• AASB S2 standard text (verbatim disclosure paragraphs with anchors): https://continuuiti.com/disclosures/aasb-s2/standard-text/
• AASB S2 worked-disclosure hub: https://continuuiti.com/disclosures/aasb-s2/