GRI, ISSB, ESRS Comparison in June 2026

Three frameworks. Overlapping scopes. Different audiences. And increasing pressure to address several of them simultaneously.

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The choice of ESG framework lies at the intersection of regulatory obligation, investor expectations, and strategic positioning.

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This comparison highlights: the framework you choose matters less than the infrastructure you use to manage it.

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This guide compares GRI, ISSB, and ESRS based on what truly matters: who they address, what they measure, and how they relate to each other. And why the real question isn't "which framework to choose?" but "are we able to manage our non-financial data regardless of the required framework?"

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Three frameworks, three starting questions

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Before comparing them, it's essential to understand what fundamentally distinguishes them. These three frameworks don't just measure different things. They start from different questions.

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• ‍GRI asks: what are the impacts of this company on the world? It's a stakeholder-oriented approach. The company must report to a broad range of stakeholders: employees, communities, civil society, and not just financial markets.

• ISSB asks: what sustainability-related risks and opportunities affect the financial performance of this company? It's an investor-oriented approach. Materiality is financial: what matters is what affects the company's value.

• ESRS asks both questions simultaneously. This is the principle of double materiality : the company must assess both its impacts on people and the environment, and the financial risks and opportunities that sustainability issues present to it.

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This difference determines which topics you report on, which data points you collect, and how you structure your internal sustainability governance.

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GRI: The Global Benchmark, Still Relevant

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GRI has been the most widely used voluntary non-financial reporting framework globally for over two decades. Its modular structure, with universal standards complemented by topic-specific standards, allows companies to report on the sustainability issues most relevant to their operations.

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Its strength lies in its international recognition. GRI reports are recognized across all geographies and sectors. For a company operating internationally without a dominant regulatory obligation, GRI remains a solid starting point.

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Its limitation in 2026: GRI was designed for narrative transparency, not for financial comparability. It does not produce the structured data that financial markets and regulators now demand.

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GRI has responded to this evolution by working on alignment with ESRS. In November 2024, EFRAG and GRI published the final version of theGRI-ESRS Interoperability Index, complemented by a GRI-ESRS linkage service available upon request. Companies already reporting under GRI can leverage this alignment to facilitate their transition to ESRS, without starting from scratch.

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ISSB: The Investor Standard Gaining Traction Outside Europe

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The ISSB standards, IFRS S1 for general sustainability disclosures and IFRS S2 for climate-related disclosures, were published in June 2023 and have since been adopted or are in the process of being adopted in the United Kingdom, Canada, Australia, Singapore, Japan, and many other countries.

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The ISSB is explicitly designed for capital markets. Its architecture relies heavily on the TCFD framework, which formally dissolved its operations in October 2023, with the ISSB taking over its monitoring responsibilities from 2024. Companies that structured their reporting around the TCFD therefore have a solid foundation for complying with the ISSB.

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The key concept is financial materiality : only financially significant information for the company must be disclosed. This makes ISSB reports more targeted than GRI or ESRS reports, but also narrower. A company with major environmental impacts that do not yet translate into financial risk would report very little under ISSB.

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For European companies, the ISSB is less immediately pressing than the ESRS. However, for multinationals raising capital or operating in markets where the ISSB is adopted, alignment with this standard becomes a practical requirement. ESRS E1 and IFRS S2 share a high level of alignment on climate: rigorous ESRS E1 reporting satisfies most IFRS S2 requirements without additional data point collection.

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ESRS: The Most Demanding Standard

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If you are a large European company, or a company within the value chain of a large European company, ESRS are no longer optional. The CSRD makes ESRS reporting mandatory, and its progressive rollout means that tens of thousands of companies are now within its scope.

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Following the Omnibus Directive, definitively adopted on February 24, 2026, and effective March 18, 2026, the direct application threshold has been tightened to companies exceeding simultaneously 1,000 employees and €450 million in turnover.

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The ESRS are structurally the most comprehensive of the three frameworks. They include cross-cutting standards (ESRS 1 and ESRS 2) establishing general principles and disclosure requirements, followed by thematic standards covering environment (E1 to E5), social (S1 to S4), and governance (G1).

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The double materiality is at the heart of ESRS compliance. Before determining what to report, companies must systematically identify their material impacts, risks, and opportunities (IROs).

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The ESRS are also currently under revision: a delegated act is expected by mid-2026, which could adjust certain disclosure requirements. It is recommended to follow EFRAG publications in parallel with your process.

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How the three frameworks interrelate

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The relationship between GRI, ISSB, and ESRS is often presented as competitive. It is not. These frameworks are complementary, and standard-setting bodies have actively worked to make them interoperable.

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Here's how they specifically interrelate:

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ESRS and GRI share a high level of alignment. EFRAG and GRI co-developed the ESRS with the aim of maximizing interoperability. A GRI-ESRS Interoperability Index has been publicly available since November 2023, identifying correspondences between the disclosure requirements of the two frameworks. For companies already reporting under GRI, many existing data points can feed into the ESRS without new data collection.

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ESRS and ISSB strongly converge on climate. ESRS E1 was explicitly designed with IFRS S2 interoperability in mind. Rigorous ESRS E1 reporting will satisfy most IFRS S2 requirements. The main divergence concerns scope: ESRS requires double materiality, while ISSB only requires financial materiality. On the social pillar, however, alignment remains limited between the two frameworks.

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GRI and ISSB address different audiences and do not directly compete. A company can use GRI for transparency with its stakeholders and ISSB for financial reporting to investors. These two exercises are not redundant.

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These frameworks are not mutually exclusive choices.

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So, which framework should you choose?

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There is no universal answer. But there are clear decision criteria.

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If you are a large European company, ESRS are your primary framework. They are mandatory, comprehensive, and integrate the core requirements of both GRI and ISSB. Build your governance architecture around ESRS and map other frameworks accordingly.

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If you are a non-European company raising capital or operating in markets where ISSB is adopted, ISSB is your anchor. Focus on financial materiality, build robust climate disclosures aligned with IFRS S2, and use GRI in a targeted way for stakeholder transparency.

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If you are a smaller company, outside the direct scope of CSRD, GRI remains the most pragmatic starting point. It is flexible, internationally recognized, and provides a foundation that you can evolve as regulatory requirements become clearer.

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If you operate across multiple geographies or serve investors with different expectations, you will likely need to report under multiple frameworks simultaneously.

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The choice of framework is secondary. The management infrastructure is decisive.

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Managing multiple frameworks in parallel with distinct collection campaigns for each multiplies costs, risks of inconsistency, and team workload. This is also the situation most organizations find themselves in today.

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The fundamental distinction is not between GRI, ISSB, and ESRS. It is between two architectures:

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• The reporting architecture : you collect data points to produce a report. When a new framework is requested, you launch another collection campaign.
• The management infrastructure : you continuously govern your non-financial data. Frameworks are a layer of interpretation for this data, not the starting point for collection.

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The first architecture creates fragmentation. The second creates an asset.

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In Harnest, the main ESG frameworks are mapped onto a common data architecture. A data point collected once can feed multiple frameworks simultaneously, within the same collection campaign.

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When a new framework is requested by an investor or a key account client, you don't have to launch a complete collection campaign again. You activate the corresponding data points on an already structured and governed basis.

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This is the logic that makes multi-framework management sustainable in the long term, and that transforms regulatory constraints into strategic capabilities.

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What 2026 truly demands

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The regulatory environment is not static. CSRD implementation is ongoing. ISSB adoption is accelerating outside Europe. And the pressure for comparable and auditable non-financial data is intensifying across all frameworks.

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The companies that will succeed are not those that choose the simplest framework. They are the ones that build a robust management infrastructure, capable of serving multiple audiences simultaneously: investors, regulators, key accounts, stakeholders.

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The framework you use today is not the only one you'll use tomorrow. So the question isn't "which one to choose?" but "will your management infrastructure allow you to respond to all the ones you'll be asked for?"

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