ISSB vs CSRD

The materiality difference — the fundamental divide

The most important difference between ISSB and CSRD is materiality:

ISSB financial materiality: Information is material if omitting or misstating it could reasonably affect the decisions of primary users of general purpose financial reports — primarily investors, lenders, and creditors. The question is: does this sustainability issue affect the company's financial condition, performance, or prospects?

CSRD double materiality: Information is material if it meets EITHER the financial materiality threshold (same as ISSB) OR the impact materiality threshold — significant positive or negative impacts on people or the environment, regardless of financial consequence.

In practice: Every disclosure required by ISSB is also required by CSRD (financial materiality is a subset of double materiality). But CSRD requires additional disclosures that ISSB does not — specifically, significant impacts on society and the environment that have no financial consequence to the company.

Example: A company's supply chain child labour impact is material under CSRD impact materiality (significant harm to people) even if there is no current financial risk. Under ISSB, this is only material if there is a financial risk — reputational damage, regulatory action, supply chain disruption. CSRD requires disclosure regardless; ISSB requires disclosure only if financial materiality is triggered.

Topic coverage — what each framework requires

Climate change (ESRS E1 / IFRS S2): ~75% content overlap. CSRD is broader — adds impact materiality dimension, XBRL tagging, mandatory assurance from year one. ISSB adds SASB industry-specific metrics.

Biodiversity (ESRS E4 / no ISSB equivalent): ISSB has no mandatory biodiversity standard. CSRD ESRS E4 is unique to CSRD. Companies reporting only under ISSB have no mandatory biodiversity disclosure obligation.

Water (ESRS E3 / no ISSB equivalent): Same — ISSB has no mandatory water standard. Water-related risks may be disclosed under IFRS S1 if financially material, but there is no IFRS S3 water standard.

Workforce (ESRS S1 / no ISSB equivalent): ISSB has no workforce-specific standard. CSRD ESRS S1 is unique to CSRD.

Governance (ESRS G1 / no ISSB equivalent): ISSB covers governance through IFRS S1 general requirements but has no anti-corruption or payment practices equivalent to ESRS G1.

Conclusion: CSRD is substantially broader than ISSB. A company fully compliant with CSRD/ESRS is approximately 70% compliant with ISSB for climate — but there is no reverse equivalence. ISSB compliance does not imply CSRD compliance.

Practical dual reporting — the efficient approach

For companies subject to both CSRD and ISSB, the most efficient approach is CSRD-first:

Step 1: Complete full CSRD/ESRS disclosure including double materiality assessment, all material ESRS standards, XBRL tagging, and third-party assurance.

Step 2: Map ESRS disclosures to IFRS S1/S2 requirements using the ISSB-EFRAG interoperability guidance. Identify which ESRS sections satisfy each IFRS paragraph.

Step 3: Identify gaps — primarily SASB industry metrics (required by IFRS S2 but not ESRS) and any jurisdiction-specific formatting requirements.

Step 4: Prepare supplementary ISSB disclosures for the gap areas — typically a relatively modest additional effort.

Step 5: Publish a single integrated report with a dual-framework content index showing which sections satisfy CSRD and which satisfy ISSB/S2 requirements.

This approach avoids preparing two separate reports and minimises duplication. The incremental cost of adding ISSB compliance to an ESRS-compliant report is approximately 20–30% of the total reporting effort — significantly less than starting from scratch for each framework.

Frequently asked questions