ESRS and ISSB Interoperability: What the Single-Report Approach Means for Multinationals

Multinationals subject to both the IFRS Sustainability Disclosure Standards (ISSB Standards) and the European Sustainability Reporting Standards (ESRS) are under growing pressure to rationalize their reporting obligations. A new analysis published by EY Tax on 26 June 2026 confirms that interoperability between the two frameworks has improved, particularly with the draft revised ESRS, but that material differences persist. The practical upshot for accounting firms, auditors, and CFOs: a single-report approach is achievable, but only with deliberate early action on governance, data infrastructure, and jurisdictional monitoring. This matters beyond sustainability teams alone, since the same structural questions arising in sustainability disclosure directly parallel the challenges firms face building reliable crypto financial statements under fragmented global standards.

Why Interoperability Matters Now

The term "interoperability" describes the degree to which two sets of reporting standards are compatible enough that a single report can satisfy both without material rework. For ISSB Standards and ESRS, the ambition is a "report once, use many times" model, reducing the duplicative cost of preparing parallel sustainability disclosures for different regulators and investor audiences.

The EY analysis identifies several reasons why multinationals are increasingly drawn to this approach. An ESRS-reporting parent might have ISSB-reporting subsidiaries. An ISSB-reporting parent might have EU-based entities subject to ESRS. Dual-listed groups may face both regimes simultaneously. And even where a group is primarily an ESRS reporter, it may voluntarily apply ISSB Standards to improve comparability for non-EU investors.

The Draft Revised ESRS and What Changed

The draft revised ESRS has narrowed certain gaps between the two frameworks. Climate-related disclosure requirements are the area of closest alignment: nearly all ISSB climate disclosure requirements now have corresponding provisions in ESRS, including requirements to disclose a transition plan where one exists. Both frameworks share broadly consistent terminology and similar disclosure structures, which means an entity can anchor its reporting in either framework and then address the incremental requirements of the other.

That said, the EY analysis is explicit that satisfying one framework does not automatically ensure compliance with the other. The gaps that remain are not cosmetic. They include differences in materiality definitions, the scope of topical and industry-specific standards, and the availability of reporting reliefs. Firms advising clients on this need to treat interoperability as a starting point for analysis, not a safe harbour.

Key Differences Firms Cannot Ignore

Three areas of divergence stand out from the EY analysis and deserve close attention from accounting and audit teams.

Materiality

ISSB Standards use a single-materiality lens focused on information that is financially material to investors. ESRS applies a double-materiality concept, requiring disclosure of both financial materiality and impact materiality (the entity's effect on people and the environment). This is not a minor technical distinction. It drives which topics must be reported, which data points must be collected, and how assurance providers scope their work. A group that treats its ISSB-compliant climate disclosure as automatically sufficient for ESRS is likely to have gaps on the impact-materiality side.

Topical and Industry Standards

ISSB has developed industry-based standards that require specific disclosures depending on sector. ESRS takes a different approach to topical standards. Where the two sets of topical requirements do not map cleanly onto each other, groups will need jurisdiction-specific layers appended to the core report, rather than a truly unified document.

Reliefs and Transitional Provisions

Both frameworks include relief provisions, but they are not identical. Reliefs available under ESRS may not have a direct equivalent under ISSB Standards, and vice versa. An entity that relies on a transitional relief under one framework should not assume that relief applies when the report is also intended to satisfy the other.

ISSB Passporting: A Promising but Incomplete Development

One of the more significant structural developments covered in the EY analysis is the concept of ISSB passporting. The idea is that a sustainability report prepared fully in accordance with ISSB Standards, without local modifications, could be recognized by multiple jurisdictions as satisfying their own regulatory requirements. This is the formal expression of the "report once, use many times" ambition at a jurisdictional level.

What Passporting Would Require in Practice

The EY analysis sets out three conditions for passporting to function. First, each jurisdiction must formally agree to recognize an ISSB-compliant report as sufficient. That requires positive regulatory action in each market, and it has not happened universally. Second, the financially material investor-relevant information must remain clearly identifiable within the report and not be obscured by additional local disclosures layered on top. Third, passporting does not eliminate ongoing local monitoring: some jurisdictions may still require supplemental disclosures or carry distinct assurance requirements.

Critically, the EY analysis flags that it remains unclear whether and how ISSB passporting can be applied when a group is simultaneously reporting under ESRS. The double-materiality and impact disclosure requirements of ESRS go beyond what ISSB Standards require, so an ESRS-compliant report is not the same document as an unmodified ISSB report. Until regulators resolve this question, groups subject to both frameworks cannot rely on passporting as a solution.

For accounting firms advising multinational clients, the takeaway is straightforward: passporting is worth monitoring closely, but it cannot be built into a current-year reporting strategy without jurisdiction-by-jurisdiction confirmation that the relevant authority has formally adopted it.

The Four Strategic Benefits of a Single-Report Approach

The EY analysis identifies four reasons why building toward a single-report approach is strategically sound even where full interoperability is not yet achieved. These benefits map directly onto the advisory value that accounting firms can offer clients working through this transition.

Reduced Complexity and Cost

Streamlining sustainability data collection and disclosure across frameworks reduces duplication in the reporting process. Where a group currently maintains parallel data pipelines for ISSB and ESRS, consolidating these into a shared core model lowers ongoing compliance costs and improves data quality. The same principle applies to digital asset reporting: firms that build a unified data architecture for crypto financial statements across multiple frameworks avoid the same duplication problem at a smaller scale.

Stronger Governance and Oversight

Embedding sustainability within group-level governance and financial planning, rather than treating it as a standalone compliance exercise, improves visibility into risks and opportunities. This is increasingly relevant for CFOs managing treasury positions that include digital assets, where the governance questions around fair value measurement and disclosure (familiar territory in IFRS crypto assets accounting) overlap with the broader sustainability governance agenda.

Regulatory Resilience

A reporting architecture designed to absorb incremental jurisdictional requirements without wholesale rebuilding is more resilient as standards evolve. The UK, Japan, and Australia have each adopted ISSB Standards as a baseline with local modifications. Groups that build a flexible core model now are better positioned to absorb those modifications as they become mandatory in each market. This is analogous to how firms currently managing Switzerland and the OECD digital economy tax framework need a flexible cross-border compliance architecture rather than jurisdiction-by-jurisdiction point solutions.

Scalable Reporting Capability

Internal capabilities built around a unified core model scale more efficiently as investor and regulatory expectations rise. This is particularly relevant for accounting firms growing their sustainability assurance practices: the skills and data-quality disciplines required for ISSB and ESRS assurance are largely the same, and a single-model approach allows firms to deploy those skills without redundant workstreams.

Practical Steps for Accounting Firms and CFOs

The EY analysis makes clear that multinationals can take structured, proactive steps toward a single-report approach regardless of which framework they currently report under. The pathways differ depending on whether an entity is moving from ESRS toward ISSB reporting or the reverse, but the underlying disciplines are consistent.

Governance Alignment

The first step is aligning sustainability reporting governance with group-level financial governance. This means ensuring that the teams responsible for sustainability data collection are connected to the finance function, not operating in isolation. For groups with digital asset positions, this connection is already critical for accurate crypto financial statements: the same data quality controls that support IFRS crypto assets fair value disclosure under IAS 38 or the IASB's forthcoming amendments need to feed into the broader sustainability data environment.

Data Infrastructure

Building a shared data reporting infrastructure that can serve both ISSB and ESRS requirements from a single source is the central operational challenge. This requires mapping the data points required by each framework, identifying where they overlap and where they diverge, and designing collection processes that capture both without creating parallel manual workstreams. Firms advising on Norway's CARF implementation and automated crypto reporting obligations will recognize the same principle: automated, structured data pipelines are more reliable and auditable than manual consolidation.

Materiality Assessment

Because ISSB and ESRS use different materiality concepts, the materiality assessment must be designed to capture both dimensions from the outset. A financial-materiality-only assessment will leave ESRS impact-materiality gaps. A double-materiality assessment designed for ESRS will likely satisfy ISSB's narrower test, making it the more efficient starting point for groups subject to both frameworks.

Assurance Planning

The EY analysis notes that obtaining assurance alongside a single-report approach brings additional complexity. Assurance providers will need to understand the interoperability claims being made in the report and assess whether the evidence base supports compliance with both frameworks. Accounting firms building sustainability assurance practices should plan for this complexity now, particularly given that assurance requirements for ESRS are already in force for larger entities in scope of the Corporate Sustainability Reporting Directive.

Implications for Digital Asset Reporting

While the ESRS and ISSB interoperability discussion is primarily a sustainability reporting question, it has a structural parallel for accounting firms and CFOs managing digital asset positions. The fragmentation between IFRS and US GAAP on crypto accounting, including the treatment of IFRS crypto assets under IAS 38 versus the FASB crypto fair value model under ASC 350-60, creates a comparable interoperability problem at the financial statement level. A multinational group that holds bitcoin or other digital assets and reports under both IFRS and US GAAP faces the same fundamental challenge as a sustainability reporter subject to both ISSB and ESRS: the two frameworks are not identical, a single set of underlying data can often satisfy both, but the differences require specific attention rather than assumption.

The lesson from the sustainability reporting context is applicable here. Build a core reporting architecture around the more demanding framework, understand the incremental requirements of the other, and design data collection to serve both from a single source. For crypto financial statements, that means ensuring the underlying transaction data, fair value sources, and classification decisions are documented in a way that supports both IFRS and GAAP disclosures without rebuilding the evidence base from scratch for each reporting currency.

Firms using digital asset accounting software to manage client crypto positions should confirm that the outputs can be mapped to the disclosure requirements of both frameworks, and that the audit trail is sufficient to support assurance under either regime. This is the same infrastructure discipline that the ESRS and ISSB single-report guidance recommends for sustainability data.

Source: EY Tax