The rapid evolution of sustainability disclosure frameworks has driven an equally urgent need for digital standardisation in ESG reporting. The eXtensible Business Reporting Language (XBRL) is at the heart of this transformation, enabling companies to submit sustainability information in machine-readable formats that enhance transparency, comparability, and accessibility across markets. In the European Union, the European Financial Reporting Advisory Group (EFRAG) and other global bodies such as the Global Reporting Initiative (GRI) are leading efforts to build XBRL taxonomies that support digital sustainability reporting under frameworks like the Corporate Sustainability Reporting Directive (CSRD) and European Sustainability Reporting Standards (ESRS) [1][2][3][4][6].

What Is XBRL and Why It Matters for ESG

XBRL is an open, international standard for the digital exchange of business information. It structures data through a system of tags, known as taxonomies, that enable sustainability and financial reports to be processed, compared, and analysed automatically. By converting human-readable disclosures into structured data, XBRL ensures that corporate sustainability information is not only transparent but also interoperable across jurisdictions and reporting frameworks.

In the ESG context, XBRL’s benefits are twofold. First, it allows investors, regulators, and stakeholders to retrieve, aggregate, and analyse data rapidly across thousands of companies. Second, it enhances data integrity and accessibility, ensuring that sustainability information can be reused efficiently for compliance, benchmarking, and assurance purposes. As global sustainability regulations expand, XBRL has become indispensable in harmonising the growing volume of ESG data being reported.

XBRL and the European Sustainability Reporting Standards (ESRS)

Under Article 29d of the EU Accounting Directive, as amended by the CSRD, companies must prepare their management reports in an electronic reporting format and digitally tag their sustainability disclosures. To facilitate this, the European Commission tasked EFRAG with developing XBRL taxonomies that translate ESRS disclosure requirements into digital, machine-readable formats [1][2].

EFRAG’s XBRL work covers three primary reporting areas:

1. ESRS Set 1 Taxonomy – Adopted by the European Commission in July 2023 and published in the EU Official Journal in December 2023, this taxonomy digitally encodes the ESRS disclosure requirements to ensure interoperability with reporting tools. It was delivered to the European Securities and Markets Authority (ESMA) and the European Commission in August 2024, forming the foundation for forthcoming Regulatory Technical Standards (RTS) governing sustainability tagging [2].
2. Article 8 Taxonomy (EU Taxonomy Regulation) – This taxonomy supports disclosure requirements under Regulation (EU) 2020/852 and its Delegated Regulation (EU) 2021/2178, covering how companies report environmentally sustainable economic activities. EFRAG handed over this taxonomy to the EC and ESMA in August 2024 as part of the broader effort to ensure the EU Taxonomy’s environmental disclosures can be reported digitally [3].
3. VSME Digital Template and XBRL Taxonomy – Developed to support the Voluntary Sustainability Reporting Standard for non-listed SMEs (VSME), adopted by the European Commission in July 2025, this taxonomy is designed to simplify digital sustainability reporting for smaller businesses. It enables SMEs to complete standardised templates that can be automatically converted into machine-readable XBRL files, reducing complexity and improving reporting quality [4].

Once adopted as part of the European Single Electronic Format (ESEF), these XBRL taxonomies will underpin the EU’s system for digital tagging of sustainability data, ensuring consistency with financial reporting and enabling integration into the European Single Access Point (ESAP).

EFRAG XBRL Development Areas	Regulatory Basis	Purpose
ESRS Set 1 XBRL Taxonomy	Commission Delegated Regulation (EU) 2023/2772	Digitises ESRS sustainability statements for all large and listed companies.
Article 8 XBRL Taxonomy	Regulation (EU) 2020/852 & Delegated Regulation (EU) 2021/2178	Translates EU Taxonomy disclosures into digital format.
VSME XBRL Taxonomy	Voluntary Sustainability Reporting Standard for SMEs (2025)	Simplifies ESG reporting for non-listed SMEs.

The Broader Ecosystem: ESMA and XBRL Europe

EFRAG’s taxonomies are being developed in coordination with ESMA, which will prepare the Regulatory Technical Standards (RTS) for tagging sustainability statements. These RTS will ultimately be adopted by the European Commission via a Delegated Act, amending Regulation (EU) 2019/815 on the European Single Electronic Format (ESEF) [1][2].

Beyond EFRAG’s efforts, the XBRL Europe Sustainability/ESG Working Group, established in 2019, plays a vital role in aligning ESG data digitisation across the continent. Co-chaired by representatives from XBRL Netherlands and DFIN, the group focuses on harmonising digital ESG disclosures, supporting the electronic filing and analysis of non-financial data, and collaborating with institutions such as EFRAG and ESMA [5]. Its ongoing initiatives include developing whitepapers, engaging with policymakers, and providing guidance on implementing XBRL-based ESG reporting in Europe.

GRI’s Digital Taxonomy: Advancing Global Interoperability

In parallel with European developments, the Global Reporting Initiative (GRI) has launched its own Sustainability Taxonomy, offering a machine-readable version of all GRI Standards. This initiative enables companies to produce digital sustainability reports that are compatible with the XBRL-based taxonomies of the ESRS and International Sustainability Standards Board (ISSB) [6]. The GRI’s taxonomy enhances data comparability and global interoperability, allowing organisations to share structured sustainability data that can be analysed consistently across regions.

According to the GRI, its new taxonomy will help close the gap between reported impacts and users’ ability to interpret them, improving data quality and analytical speed. Training programmes and validation tools, expected by late 2025, will support companies and third-party service providers in adopting digital sustainability reporting [6].

Digital Tools for SMEs: The VSME Converter

A notable innovation emerging from EFRAG’s digitalisation efforts is the Digital-Report-to-XBRL Converter, designed for the VSME framework. The converter transforms Excel-based sustainability templates into tagged Inline XBRL reports and validates them using full XBRL specifications. The tool is open-source, licence-free, and adaptable for integration across different platforms, democratising access to digital reporting technology for small and medium-sized enterprises [4].

The Future of XBRL in ESG Reporting

As sustainability reporting shifts from narrative to data-driven disclosure, XBRL stands as the foundation of a digitally connected ESG ecosystem. The integration of ESRS, EU Taxonomy, and GRI digital standards into interoperable XBRL taxonomies will allow regulators and investors to access high-quality ESG data in real time, improving risk assessment and market efficiency.

Digital tagging will become mandatory once the European Commission adopts EFRAG’s XBRL taxonomy into law under the ESEF framework, a move expected to transform how sustainability information is reported, exchanged, and verified. By enabling machine-readable ESG reporting, XBRL will help bridge the gap between corporate disclosure and stakeholder accountability, setting a global precedent for transparency and comparability in sustainable finance.

Sources:
[1] EFRAG. Digital Reporting with XBRL (2024). Available at: https://www.efrag.org/en/sustainability-reporting/esrs-workstreams/digital-reporting-with-xbrl
[2] EFRAG. ESRS XBRL Taxonomy (2024). Available at: https://www.efrag.org/en/projects/esrs-xbrl-taxonomy/concluded
[3] EFRAG. Article 8 XBRL Taxonomy (2024). Available at: https://www.efrag.org/en/projects/article-8-xbrl-taxonomy/concluded
[4] EFRAG. VSME Digital Template and XBRL Taxonomy (2025). Available at: https://www.efrag.org/en/vsme-digital-template-and-xbrl-taxonomy
[5] XBRL Europe. ESG/Sustainability Working Group (2022). Available at: https://www.xbrleurope.org/?page_id=2883
[6] ESG Today. GRI Launches Digital Taxonomy to Enable Machine Readable Sustainability Disclosures (2025). Available at: https://www.esgtoday.com/gri-launches-digital-taxonomy-to-enable-machine-readable-sustainability-disclosures/