What Is ESEF?

What Is the ESEF Mandate?

The ESEF mandate is the mandatory electronic reporting format for issuers on regulated markets and sets out how an annual financial report must be prepared and presented for filing. The regulation has been in place since 2021. Companies listed on an EU-regulated market must prepare annual financial reports in a structured format that meets the relevant electronic reporting format and reporting requirements. Issuers prepare the report as an XHTML document and tag the figures in the consolidated financial statements with the ESEF Taxonomy. ESMA, the European Securities and Markets Authority, defines the mandate and related rules, which are transposed and implemented by the EU states. The introduction of ESEF is one of the biggest changes in European financial reporting in recent years.

Who Is Required to Comply with ESEF?

ESEF applies to issuers whose securities are admitted to trading on regulated markets across the European Economic Area (EEA), as well as the UK, and who prepare consolidated annual financial reports. In practice, the ESEF requirements apply to listed companies with securities admitted to trading on an EU-regulated market. That covers most listed companies on EU exchanges, plus third-country issuers whose home market for regulatory purposes is in the EU.

Companies on multilateral trading facilities or other unregulated markets fall outside the mandate. UK-listed issuers report under the UK regime, UKSEF, explained more below.

What Is the ESEF XBRL Taxonomy?

The ESEF taxonomy is the dictionary of tags a filer chooses from. It contains specific elements for classifying financial information consistently, so “revenue” tagged by a French retailer means the same thing as “revenue” tagged by a German bank.

ESMA maintains the taxonomy and builds it on the IFRS taxonomy produced by the IASB, with guidance on how it should be used. Where an issuer reports a figure that has no standard tag, the issuer creates extension taxonomy elements when needed and anchors them to the closest existing concept.

What Changes Happen Each Year?

ESMA updates the ESEF taxonomy each year in line with the IFRS Taxonomy and market developments, adding or retiring tags as needed. Filers use the version that applies to their reporting period, so each annual cycle starts with a check on which taxonomy releases are available, as set out in the applicable Regulatory Technical Standards (RTS). Typically, the prior year RTS is applicable, but early adoption of the latest RTS is permitted.

A recent release added support for IFRS 18, the new standard on presentation and disclosure that replaces IAS 1 from 2027.

What Is Next for ESEF?

Three developments will shape ESEF over the next few years. The first is sustainability reporting, as ESEF reporting is evolving to include tagging of sustainability information in line with the Corporate Sustainability Reporting Directive. ESMA has proposed bringing this into the framework through the European Sustainability Reporting Standards and disclosures required under Article 8 of the EU Taxonomy Regulation. The 2026 Omnibus I package cut both the scope and the number of data points. The UK is taking a separate route based on the ISSB standards, which is where the main disclosures required by ESEF and UKSEF start to diverge.

The second development is ESMA’s intention to extend the tagging of financial information to the detailed tagging of the notes. ESMA originally consulted on this in its December 2024 draft RTS. This will make ESEF reports more valuable to data users.

Both of these changes are intended to enhance transparency for stakeholders.

The final upcoming development is the European Single Access Point (ESAP), the EU’s central portal for company disclosures. ESMA must have it running by July 2027, with data phased in afterwards. ESAP gives tagged ESEF data a single public home, and is covered in more detail in the data section below.

What Is UKSEF? The UK Variant of ESEF

UKSEF is the UK Single Electronic Format, the UK’s version of ESEF. The Financial Reporting Council (FRC) maintains UKSEF and extends the ESEF taxonomy with UK-specific tags. Those extra tags serve the Financial Conduct Authority (FCA) for regulatory filing and Companies House for statutory filing.

How Does UKSEF Differ from ESEF?

The differences are UK-specific. They include additional sections to the taxonomy from the FRC, which enable preparers to tag the Strategic Report, the Directors’ report, the Audit report and the Streamlined Energy and Carbon Reporting disclosures. UKSEF enables the tagging of the parent company’s financial statements using the applicable FRC taxonomy. UKSEF also tags the company registration number and period end date that Companies House requires, so a single document can satisfy both the FCA and Companies House. 

The two formats stay close for now and are expected to move apart over time. The clearest split ahead is sustainability reporting, where the EU follows the EFRAG-defined ESRS while the UK will follow standards based on the ISSB framework.

Who Needs to Comply with UKSEF?

No company has to use UKSEF specifically unless they choose to use their regulatory filing to the FCA as their Companies House filing as well. UK issuers on the Main Market of the London Stock Exchange must file their annual report in a digital format under the FCA’s DTR 4.1 rules, and they can choose either UKSEF or ESEF to do it.

UKSEF is the broader of the two and the usual choice for UK filers, because as explained above, it covers additional areas and supports a single filing to both the FCA and Companies House. ESEF on its own is enough for FCA compliance but Companies House has additional tagging requirements which are enabled only by UKSEF.

What Does ESEF Compliance Require?

A compliant ESEF filing is an XHTML report with iXBRL tags on the consolidated financial statements and block tags on the notes. Software handles the conversion, the tagging, and the validation against ESMA’s rules and applicable ESEF RTS before companies submit the report to the regulator or official repository. ESMA also publishes an ESEF Reporting Manual which offers additional guidance. Software implements this too, using the accompanying conformance suite.

XHTML Format for Annual Financial Reports

ESEF reports are filed as XHTML, the same document format that web pages use, supporting electronic reporting of annual financial reports. Any browser can open the file, so a reader sees the annual report laid out as designed in a human-readable form while remaining machine-processable.

A company keeps its charts, photographs, and layout from the source document, and the filed version looks the same to a reader. The iXBRL tags generally stay invisible behind the figures, read by software but never shown on screen. However, as the useful ability to search the data layer manually becomes more recognised, the latest interactive iXBRL viewers allow readers to see both the format and the tags to aid discovery of required information.

ESEF iXBRL Tagging for Consolidated Financial Statements

The primary financial statements get the most detailed treatment. Each figure in the consolidated statement of comprehensive income, statement of financial position, statement of cash flows, and statement of changes in equity gets its own tag from the ESEF taxonomy.

A tag defines what the number means, so software reads it as the same concept reported by any other ESEF filer. Tags at this level of detail improve comparability across companies and turn a static report into machine-readable financial information that investors and other stakeholders can search and compare more efficiently.

Block Tagging Requirements

The notes to the financial statements are handled with block tagging. The RTS provides a list of about 250 tags which have to be applied in the annual report if the corresponding disclosures are present.

The notes came into scope after the primary statements, for financial years starting on or after 1 January 2022. Some blocks nest inside others, where a tagged section falls within a larger tagged note, and the software keeps that structure intact.

How to Find and Use ESEF Data?

ESEF tags have a use after the filing is done. The tags make every figure in the report findable and machine-readable, so the filed document becomes a source of structured data for analysts, investors, and software.

This section covers what that data is good for, where filings are published, how to search and extract them, and where the EU is taking public access next.

The ESEF Data Set and Benefits to AI

A tagged report is data a computer can read with no guesswork. Each figure has a defined meaning, so software can search and accurately compare financial information across companies directly and improve transparency, with none of the time consuming and unreliable extraction an untagged PDF forces.

That structure suits AI well. A model that works from tagged data starts with figures whose meaning is already settled by the preparer, which makes a misread or misunderstood number less likely.

CoreFiling’s view is that the tag is a human judgement about what the data means, and that judgement is what keeps automated analysis trustworthy.

ESEF data can be exported in machine-friendly formats such as XBRL-JSON and XBRL-CSV, ready for analysis tools and data pipelines.

National Officially Appointed Mechanisms (OAMs)

Each EU and EEA country runs an Officially Appointed Mechanism (OAM), the national store where regulated company information is published and kept. When an issuer files its annual report, the report reaches the public through its home country’s OAM.

ESMA maintains a register that maps to every national OAM, so a single list can be used to identify filings from any market. In the UK, the equivalent store is the FCA’s National Storage Mechanism.

CoreFiling: Search and Extract and the AI Data Librarian

CoreFiling builds tools to use ESEF data, as well as to create it. The True North Data Platform searches tagged filings and extracts the data behind them, so a user can query many reports at once and take out the figures they need without the need to read each document by hand.

The same structure that makes a filing compliant makes it searchable. Once the tags are in place, a question like “show me Revenue for these fifty companies” turns into a quick query.

The Future: The European Single Access Point

The European Single Access Point (ESAP) is the EU’s plan to gather company disclosures into one public portal. ESMA must launch it by 10 July 2027, and the data will phase in over the years that follow.

ESAP creates no new reports. It collects filings that companies already produce, such as ESEF annual reports, and makes them searchable in one place for free. Tagged data is what makes a central point like this work, since software can read and index it directly.

How CoreFiling Supports ESEF and UKSEF Compliance?

CoreFiling covers the full reporting chain, from the company that files a report to the auditor who assures it, to the regulator who collects it and to the user of the data who consumes it. The same software powers each role, which means a filer runs the same checks the regulator will run on the submission.

Every product here runs on the True North Data Platform, built on open standards so the data stays reliable as it moves between the people who create it and the people who use it.

CoreFiling’s ESEF Credentials

CoreFiling is an independent software company that has worked on iXBRL, XBRL, and XML reporting for more than 25 years. National regulators, central banks, the Big Four, and organisations in 26 countries rely on its software to meet their reporting obligations.

25+ Years of XBRL Experience

CoreFiling has built XBRL and iXBRL software since 1997 and works at the centre of the standard. The team writes specifications and shapes taxonomy best practice with XBRL International, and several of the world’s most used taxonomies were built with CoreFiling tools.

Our True North platform was the first software certified for full XBRL compliance, and it remains one of only a few providers certified for both creation and consumption.

Inventors of the iXBRL Format

CoreFiling co-developed Inline XBRL (iXBRL) with HMRC in the late 2000s, and the UK adopted it in 2010 for Corporation Tax filing. The format went on to underpin mandates worldwide, such as ESEF and UKSEF in Europe and SEC filings in the US.

Every ESEF report uses the format and standard CoreFiling helped create, and that standard is the foundation our software is built on.

Useful ESEF Resources

These external resources help you check which markets fall under ESEF, find where reports are published, and see what a finished filing looks like.

Our credentials

CoreFiling are an independent software company that has delivered iXBRL, XBRL and XML reporting solutions for more than 20 years. Major regulators, accounting firms and filers, including some of the largest companies in the world, rely on our software and services to help them achieve compliance in the easiest way possible. CoreFiling invented the iXBRL format and customers have used our software to produce hundreds of thousands of quality iXBRL documents to date. With our proven expertise and deep knowledge of the technology, we provide maximum confidence and peace of mind for any ESEF filer.