IFRS S1 and S2: how the pair works, and when it applies

IFRS S1 General Requirements for Disclosure of Sustainability-related Financial Information and IFRS S2 Climate-related Disclosures are the ISSB's first two standards, issued on 26 June 2023.

S1 sets the general requirements for all sustainability-related risks and opportunities: the materiality test, the four areas of disclosure, where and when to report, and what to do when no standard covers a topic.

S2 is the first topic standard, for climate, and adds scenario analysis, Scope 1, 2 and 3 emissions and seven cross-industry metrics.

Both are effective for annual reporting periods beginning on or after 1 January 2024 (IFRS S1 paragraph E1, IFRS S2 paragraph C1).

Earlier application is permitted only if the other standard is applied at the same time.

The ISSB's December 2025 amendments to IFRS S2 apply for periods beginning on or after 1 January 2027.

The effective date is the standards' own; whether any company must use them depends on each jurisdiction.

Not as IFRS S1 and S2.

The UK endorsed them as UK SRS S1 and S2, published by the Department for Business and Trade on 25 February 2026 for voluntary use and with no effective date.

Under the FCA's final rules (PS26/19, 30 September 2026), listed companies in UKLR 6, 14, 15, 16 and 22 must report against UK SRS on a comply-or-explain basis for accounting periods beginning on or after 1 January 2027, with first reporting in 2028.

Nothing in UK SRS is mandatory under those rules.

Yes.

IFRS S1 paragraph E1 says an entity applying it early shall apply IFRS S2 at the same time, and IFRS S2 paragraph C1 says the reverse.

In the first year IFRS S1 paragraph E5 lets an entity report on climate only — the 'climate-first' relief — and apply S1 only so far as it relates to climate, disclosing that it has done so.

The International Sustainability Standards Board, formed by the IFRS Foundation Trustees on 3 November 2021 at COP26 in Glasgow.

The ISSB operates alongside, but independently from, the IASB, which writes the IFRS Accounting Standards.

It built on the work of the CDSB, the TCFD, the Value Reporting Foundation's Integrated Reporting Framework and the SASB Standards.

In the IFRS Foundation's own words of 18 June 2026, over 40 jurisdictions 'have already decided to use or are taking steps to introduce ISSB Standards'.

On 24 February 2026 the Foundation said requirements had already come into effect in 19 jurisdictions.

The two are different claims: taking steps is not the same as reporting being required.

The Foundation's register splits jurisdictions into profiles, where the approach is final, and snapshots, where it is still in progress; the UK is a snapshot.

UK SRS S1 and S2 are IFRS S1 and IFRS S2 (as amended by the ISSB in December 2025) endorsed with a small set of differences, all listed in Annex A of the government's consultation response, which carries no count.

The effective dates were removed; references to SASB and the Industry-based Guidance changed from 'shall' to 'may'; the first-year option to publish later than the accounts was removed; the Scope 3 and climate-first reliefs lost their time limits; and paragraph B59A adds a duty to explain when financed emissions cannot be disclosed.

The standards themselves did not change in 2026; the ISSB's last amendment was to IFRS S2 in December 2025, applying from 1 January 2027.

What changed was their use: the UK published UK SRS S1 and S2 on 25 February 2026 and the FCA finalised comply-or-explain rules on 30 September 2026, while elsewhere Brazil's securities regulator revoked mandatory reporting for public companies on 29 May 2026.