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Technical Modelling of the UK and Irish Digital Reporting Taxonomies Feedback Statement
The FRC does not accept any liability to any party for any loss, damage or costs howsoever arising, whether directly or indirectly, whether in contract, tort or otherwise from any action or decision taken (or not taken) as a result of any person relying on or otherwise using this document or arising from any omission from it.
© The Financial Reporting Council Limited 2026
The Financial Reporting Council Limited is a company limited by guarantee. Registered in England number 2486368. Registered Office: 13th Floor, 1 Harbour Exchange Square, London E14 9GE
1. Executive Summary
1This paper sets out the Financial Reporting Council (FRC)'s summary of responses to the Discussion Paper 'Technical Modelling Discussion Paper', which was issued on 7 November 2025 and closed on 11 January 2026.
2All organisations report business and financial data. Traditionally, they have done this in a paper format but increasingly are reporting digitally. Digital reporting has been a part of UK disclosure processes since 2011, when HMRC and the FRC pioneered its use for companies to send their Company Tax Returns online using XBRL for accounts and computations. Every year since, the importance, scope and requirements of UK digital reporting have grown, and it now encompasses disclosures to Companies House, Financial Conduct Authority (FCA), Charity Commission of England and Wales, and the Irish Office of the Revenue Commissioners.
3Digital reporting makes use of technology to streamline the reporting process. Digital reports are prepared and presented in structured, machine-readable digital formats using specialist software designed for this purpose. Digital reports are shared electronically through dedicated reporting portals, regulatory databases, or other secure online platforms, facilitating faster and more efficient data exchange between entities and stakeholders.
4The FRC enables the creation of digital reports in inline eXtensible Business Reporting Language (iXBRL) format through the Taxonomies project. It is the collective group of technical and policy experts from regulators, agencies, arms-length bodies, software vendors, and professional services, who manage the process that turns laws and accounting standards into computer code, or taxonomies. Taxonomies make it possible to digitally disclose information in a standardised way that is intended to reduce the burden and costs to businesses by:
- creating a clearer and more user-friendly process for regulatory reporting;
- creating more efficient and effective regulation and regulators; and
- improving the accuracy, comparability, accessibility, and value of reported data for investors and other stakeholders.
Our main objectives in undertaking the discussion paper were to seek feedback from technical readers on the technical modelling changes on the structure and content of the various files that make up the UK and Irish digital reporting taxonomies. Although highly technical in nature the proposals set out in the paper are designed to reduce burden on preparers and make it easier for users to interpret the data.
5The FRC received four detailed written responses to the Discussion paper. In addition to these formal submissions, the proposed changes were extensively discussed with the XBRL Technical Task Force, which comprises representatives from various software houses and agencies operating within the UK digital reporting ecosystem. Furthermore, we consulted with software vendors operating in the Republic of Ireland to ensure the proposals continue to support efficient digital reporting to Irish Revenue and maintain the integrity of the shared taxonomy suite.
6We are grateful for the time which respondents have taken to consider the discussion paper, especially given the range and complexity of some of the topics, and for the high quality, considered, and detailed feedback we have received. Our stakeholders clearly recognise the value of digital reporting and are keen to work with us to ensure that the changes we introduce in the taxonomy modelling are pragmatic, efficient, and the data generated is a key enabler of growth and competitiveness.
7Consultation responses will inform our collective approach to the technical implications of the fundamental areas of discussion through the FRC's ongoing strategic development of the Taxonomy project.
8Responses consistently highlighted maintaining global comparability, aligning taxonomies with XBRL specifications, and embedding formulas in the taxonomy to define validation rules to support data quality.
9Some respondents recommended undertaking further cost benefit analysis before introducing changes like adding an additional entry point in the Charities Taxonomy to digitise Receipt and Payment accounts.
2. Introduction and Background
10The purpose of the FRC is to serve the public interest and support UK economic growth by upholding high standards of corporate governance, corporate reporting, audit and actuarial work.
11Since 2011, UK regulators, agencies, and government departments1 have increasingly required filers2 to digitally report financial and non-financial information in the Extensible Business Reporting Language (XBRL)3, and, later, iXBRL4. This began with HMRC's original mandate for companies to send their Company Tax Returns online using XBRL for accounts and computations, and, most recently, includes the Economic Crime and Corporate Transparency Act 2023 and Corporate Transparency and Register Reform white paper's comprehensive digital mandate for all submissions to Companies House. FCA Disclosure and Transparency Rules (originating in EU legislation) also now require IFRS financial statements within annual financial reports to be published in a structured digital format and filed in the FCA's National Storage Mechanism which is accessible to the public.
12The Discussion Paper was aimed to obtain feedback to improve the usability, scalability, and technical integrity of taxonomies, thereby making it easier for users to apply the taxonomies and reduce regulatory burden.
13As a result of the technical and specialised nature of the paper we received four detailed written responses from stakeholders and also carried out further stakeholder engagement through consultations with the XBRL Technical Task Force and technical forums with software vendors operating across the UK and the Republic of Ireland. We have reviewed all of the responses in detail and are grateful for the time and consideration many of our stakeholders gave to our proposals.
3. Summary of Responses
Responses to the discussion paper
1. Replacing fixedItemType data type with Extensible Enumerations
There was a broad consensus among respondents in support of replacing the legacy fixedItemType with the XBRL Extensible Enumerations specification. Respondents noted that this move successfully aligns the UK and Irish Digital Reporting Taxonomies with international standards, reducing the need for bespoke, UK/Irish-specific software customisations and enhancing global interoperability. Stakeholders highlighted that the current mechanism, while innovative at its inception, is now an outlier that complicates the landscape for software vendors. There was also a suggestion for leveraging XBRL International taxonomies for currencies and countries rather than maintaining UK bespoke taxonomies. This would reduce the maintenance burden on the FRC.
2. Introducing the formula linkbase
The proposal to introduce XBRL formula linkbase received unanimous support from respondents, who viewed it as a vital evolution in ensuring data quality. Respondents noted that transitioning from passive, text-based guidance to embedded validation rules reduces interpretation ambiguity for all software providers. While there was strong support for technical validations (such as Company Registration Number (CRN) formats and duplicate facts), respondents urged the FRC to prioritise business rules that are conditional based on entity size and accounting framework to avoid the proliferation of false positive errors that might prevent timely filing. Respondents recommended a phased implementation strategy, initially using warning severity levels to allow preparers to adapt without blocking submissions.
3. Expanding use of typed dimensions
The proposal to expand the use of typed dimensions, specifically for subsidiaries, associates, and joint ventures was widely supported as a necessary solution to the scalability limitations of the current taxonomy. Stakeholders agreed that moving away from predefined, numbered explicit members (e.g., Subsidiary 1 to 200) reduces the maintenance burden on the FRC and provides preparers with the flexibility to report complex entity structures. Several respondents identified further opportunities to clean up the taxonomy by converting other generic explicit dimensions, such as Major Customers, Products and Services, and Entity Officers into typed dimensions. Despite the support for increased flexibility, respondents raised significant concerns regarding data comparability and iXBRL rendering.
4. Prevent use of cross-entry point elements
Respondents acknowledged that the current taxonomy architecture with shared core schema allows software to technically access the additional element in the taxonomy that are not designed for a specific entry point, leading to frequent tagging errors, particularly in Accounts Production software that recycles templates across different accounting frameworks. To address this, respondents suggested several technical architectures, such as adopting the Negative Hypercube model used in European Single Electronic Format (ESEF) to programmatically lock out unauthorised tags or utilising XBRL Property References to metadata-tag every concept with its allowed entry points. A further proposal included implementing XBRL Formula assertions to validate tags against the Presentation Linkbase of each specific entry point, which would facilitate more descriptive and user-friendly error messaging for preparers.
5. A specific entry point to support micro-entity and small filings
Respondents pointed to using Extended Link Roles in the main taxonomy to offer the presentation of these elements without restricting access to the rest of the taxonomy. This could also support software vendors to identify relevant concepts and build products focused just on those. Other solutions focused on the roles of collectors agencies and vendors in implementation strategies, including forms, templates and spreadsheet conversion to remove the burden from preparers of these accounts.
6. Introducing Accounting Semantic Arcroles
Responses were varied. While some recognised the benefits of using these arcroles in principle, and in practice in other jurisdictions, others felt that this was not as important to stakeholders as the underlying modelling issues addressed elsewhere in the paper. Responses did not consider it likely that vendors would focus on implementing these features. The FRC was referred to the Accounting Semantic Arcroles inclusion in the Open Information Model and encouraged to engage with the upcoming Open Information Model (OIM) consultation. Responses agreed that vendors should be implementing the arcroles in XBRL Link Role Registry; if there were included there it should not be deemed burdensome to implement. Any developments in UK-custom arcroles should be submitted for consideration to the Link Role Registry to minimise UK-specific implementation burdens.
7. Digitisation of Charities Receipts and Payments accounts
Responses express general support for increasing digitisation and standardising both content and format to improve transparency and accessibility. However, they note that without a formal mandate for digitising these accounts, adoption rates among charities are expected to remain very low. In terms of technical implementation, the feedback suggests that the burden on preparers can be minimised by offering flexible submission methods such as webforms, or a hybrid of both. Respondents recommend that the Charity Commission should conduct a comprehensive cost-benefit analysis before proceeding with significant investments.
FRC Response
14The FRC remains committed to providing taxonomies that enable the efficient and effective preparation of legally compliant digital annual reports. Proposed changes will be subject to thorough review and testing to ensure they do not introduce unnecessary complexity or cost. To ensure transparency, any proposed architectural or technical changes will follow the Taxonomy Development Due Process; all such changes will be formally consulted upon via a draft taxonomy release for public consultation before final implementation.
15To fulfil the principle of leading and influencing internationally, the FRC will continue to have regard for global digital reporting standards. We aim to adopt XBRL specifications that improve interoperability with international software, ensuring the UK Taxonomy Suite remains in line with technology available in the global marketplace.
16The FRC will prioritise a scalable and maintainable taxonomy architecture that can accommodate evolving reporting needs. This includes exploring flexible modelling techniques that allow for comprehensive tagging without requiring a disproportionate increase in the number of individual tags.
17In line with the principle of reducing the burden on preparers, all proposed changes will be assessed for their impact on the reporting pipeline. We aim to ensure the Taxonomy Suite remains easy and efficient to use, balancing technical rigour with practical usability for those preparing digital reports.
Financial Reporting Council
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From this point on, we use the word "regulators" to collectively cover those signed up to the FRC's Taxonomies project: Companies House, FCA, HMRC, the Charity Commission for England and Wales, the Irish Revenue. ↩
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This paper discusses broad topics that apply to all that are responsible for preparing digital reports. For the sake of readability we use the word "filer" generically to cover the range of preparers of digital reports (i.e. listed and unlisted businesses, charities, banks, insurance companies etc.). Where further granularity is necessary, we describe the specific type of filer that would be affected. ↩
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XBRL is the open international standard for digital business reporting. ↩
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iXBRL is a hybrid format that combines both HTML (the language webpages are written in) and XBRL. It is designed to make XBRL data human-readable directly in a web browser while retaining the machine-readability of XBRL. ↩