ISSB — International Sustainability Standards Board

Definition

ISSB (“International Sustainability Standards Board”) is the IFRS Foundation’s sustainability standard-setting body, established in November 2021 at COP26 in Glasgow and formally constituted in April 2022 through amendments to the IFRS Foundation Constitution. It sits parallel to the International Accounting Standards Board (IASB) — IASB issues IFRS Accounting Standards; ISSB issues IFRS Sustainability Disclosure Standards.

The policy intent: build a single, globally consistent baseline for sustainability-related financial disclosure that investors and capital providers can rely on across jurisdictions — analogous to how IFRS Accounting Standards function as the global baseline for financial reporting.

The two standards in force

IFRS S1 — General Requirements

IFRS S1 sets the general framework for sustainability-related financial disclosure: scope, materiality assessment, reporting boundary, connected information, and disclosure of governance, strategy, risk management, and metrics + targets. It applies to all sustainability-related risks and opportunities that could reasonably be expected to affect the entity’s cash flows, access to finance, or cost of capital over the short, medium, or long term.

IFRS S2 is the first topic-specific standard. It mandates climate-related disclosure across the same four pillars (governance, strategy, risk management, metrics + targets) and requires:

Scope 1, 2, and 3 GHG emissions disclosure measured per the GHG Protocol (Scope 3 phased in with one-year relief)
Climate-related transition + physical risk identification, with scenario analysis
Targets, including any internal carbon prices used
Industry-specific metrics derived from the SASB Standards (now under ISSB stewardship)

Both standards are effective for annual reporting periods beginning on or after 1 January 2024 for jurisdictions that adopt them.

Relationship to TCFD

ISSB consolidated the global voluntary sustainability-disclosure ecosystem after its creation:

The TCFD (Task Force on Climate-related Financial Disclosures) framework was absorbed into IFRS S2 — TCFD’s four-pillar structure (governance, strategy, risk management, metrics + targets) is the architecture of IFRS S2. The TCFD was formally disbanded in October 2023; the Financial Stability Board transferred its monitoring responsibilities to the IFRS Foundation.
The SASB Standards (Sustainability Accounting Standards Board, originally industry-specific) moved under the IFRS Foundation in 2022 and now inform IFRS S2’s industry-specific guidance.
The CDSB (Climate Disclosure Standards Board) was consolidated into the IFRS Foundation in early 2022.
The Integrated Reporting Framework (originally IIRC, then VRF) was also brought under the IFRS Foundation umbrella.

The effect: post-ISSB, the previously fragmented sustainability-disclosure landscape converged into a single standard-setter with a single set of baseline standards. National regimes (EU CSRD, SEC climate disclosure, Indian BRSR) can layer additional jurisdiction-specific requirements on top of — or partially align with — the ISSB baseline.

ISSB and India

India has not yet adopted IFRS S1 or IFRS S2 as a mandatory reporting framework. The current Indian sustainability-reporting baseline is the SEBI BRSR Format + BRSR Core, which is structurally independent of ISSB:

BRSR architecture: built on the 9 NGRBC Principles, with leadership + essential indicators, and BRSR Core (9 attributes) requiring reasonable assurance for the top 1,000 listed entities (phased by market cap).
ISSB architecture: built on the TCFD four-pillar structure, with general (S1) + climate-specific (S2) standards.

The two regimes overlap on underlying data (GHG emissions, water + energy consumption, workforce metrics) but differ on disclosure structure, materiality concept (BRSR uses single materiality; IFRS S1 uses financial materiality oriented toward investors), and assurance regime.

ICAI participation: ICAI engages with the IFRS Foundation’s standard-setting process through the Sustainability Reporting Standards Board (SRSB). The SRSB has issued an Indian-context Background Material on BRSR (Revised 2024) that maps BRSR disclosures to ISSB / TCFD / GRI references where relevant, but no formal convergence roadmap has been published as of 2026.

Likely trajectory: ICAI’s SRSB and SEBI are studying ISSB alignment. Indian companies dual-listed (e.g., on US or LSE) or with significant foreign investor base often produce a separate ISSB-aligned sustainability-finance disclosure alongside the SEBI-mandated BRSR. Convergence to a single Indian baseline that fully maps to ISSB is a multi-year project; near-term Indian filers can expect to continue producing BRSR + a voluntary ISSB-aligned disclosure if their investor base demands it.

ISSB vs GRI

A common point of confusion: ISSB and GRI serve different audiences with different materiality concepts.

ISSB (IFRS S1 / S2): investor-oriented, financial materiality — sustainability matters that could reasonably affect cash flows, financing access, cost of capital.
GRI (Universal + Sector + Topic Standards): multi-stakeholder, impact materiality — the entity’s positive and negative impacts on the economy, environment, people (including human rights).

The two are designed to be complementary, not substitutive. ISSB explicitly references GRI as a starting point for entities seeking to disclose impacts beyond what financial materiality captures. The EU CSRD’s ESRS adopts a double materiality approach (combining both financial and impact materiality), and the ESRS / ISSB interoperability guidance issued jointly by EFRAG + IFRS Foundation in 2024 maps which disclosures satisfy both regimes. See the CSRD Disclosure Framework for the post-Omnibus regulatory state + India-relevance.

Assurance over ISSB-aligned disclosures

ISSB does not prescribe an assurance standard. Where entities voluntarily seek assurance over IFRS S2 climate-related disclosures, the most commonly used standard is ISAE 3000 (Revised) for the broader sustainability data and ISAE 3410 for the GHG emissions component specifically. For Indian engagements, the SAE 3410 (ICAI’s Indian equivalent of ISAE 3410) is the relevant local standard for GHG verification.

For coordination of GHG inventory + voluntary ISSB-aligned disclosure + the underlying BRSR mandatory reporting through a single partner CA firm, see BatchWise BRSR Core Assurance — the engagement scope can be configured to deliver BRSR + an aligned ISSB / TCFD package off the same data infrastructure.

Common questions

Is ISSB mandatory anywhere? Adoption is jurisdiction-by-jurisdiction. The UK, Australia, Brazil, Canada, Japan, Singapore, and others have published roadmaps requiring or endorsing IFRS S1 / S2 from 2024-2026 onwards. The EU has not adopted ISSB directly but its CSRD / ESRS regime is interoperable with IFRS S2 climate disclosures.

Does ISSB replace BRSR for Indian filers? No. SEBI’s BRSR Format + BRSR Core mandate is independent of ISSB. Indian listed entities cannot substitute ISSB-aligned disclosure for the SEBI BRSR filing.

What is the relationship between ISSB and SASB? SASB Standards (industry-specific sustainability metrics) moved to the IFRS Foundation in 2022. They now inform the industry-specific application guidance of IFRS S2 and any future ISSB topic-standards. The SASB Standards themselves remain available as a separate reference framework.

What’s the difference between ISSB and the SEC climate disclosure rule? The US SEC adopted a climate disclosure rule in 2024 covering large registrants. It is conceptually aligned with IFRS S2 (TCFD architecture) but contains US-specific scoping and materiality thresholds. The rule has faced legal challenges and is in flux; large Indian companies with US listings should track the rule’s status and effective date separately from any ISSB engagement.