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What is UKSEF? What UK-listed companies must know

The UK’s Financial Conduct Authority (FCA), has permitted to use UK Single Electronic Format (UKSEF), a taxonomy which is based on IFRS taxonomy and an extension of ESEF taxonomy to allow for the preparation of UK-specific ESEF accounts containing FRC taxonomy items, and based on the English language ESEF entry points.

What is UKSEF?

  • The inclusion of the UK’s new Streamlined Energy and Carbon Reporting (SECR) requirement, integrating Inline XBRL-based carbon disclosures with financial reporting.
  • The company’s registered number and the period end date, enable an ESEF annual report to pass through the digital gateway at Companies House.

Who has to file UKSEF?

  • In general, companies with transferable securities admitted to trading on UK regulated markets must prepare their annual financial reports in XHTML format for financial years starting on or after 1 January 2021, to publish from 1 January 2022 and to be filed with the FCA’s National Storage Mechanism (NSM).
  • All other issuers who prepare their annual consolidated accounts in accordance with International Financial Reporting Standards (IFRS), whether UK, EU or international IFRS, has to mark up those financial statements with tags selected from one of the permitted taxonomies.

When to file

FCA has suggested a phased implementation of the mandatory tagging obligations as set out in the below table:

Date Obligation Financial period
2021 Voluntary ESEF filing started. The National Storage Mechanism to accept Annual Financial Reports in ESEF. Financial years starting on or after 1 January 2020.
2022 The first phase of mandatory electronic format reporting requirements applies to in-scope issuers preparing consolidated financial statements in line with IFRS

Annual financial reports for all issuers in scope to be published and filed in an electronic format specified in our technical standards.

Mandatory tagging of basic financial information.

Financial years starting on or after 1 January 2021.



Publication from 1 January 2022.

2023 The second phase – in-scope issuers as above must also tag notes to the annual financial statements. Financial years starting on or after 1 January 2022. 

Publication from 1 January 2023.

The latest UKSEF tagging guide provides further guidance on the main principles involved in the preparation and consumption of structured reporting in the UK (under FCA DTR 4.1.14R) as per the requirements of UK regulators, the FCA and Companies House.

Currently, UKSEF is a voluntary requirement. Companies may choose either ESEF or UKSEF to tag their Annual Financial Reports (AFRs).

The FCA has made clear in advance their intention to switch over from UKSEF 2022 taxonomy v.1.0.0 to v.2.0.0 at the start of May 2022.

If any company decides to file using UKSEF, then the UKSEF 2022 taxonomy has to be used for reports having a financial year starting from 1 January 2022 and must use the latest version, v2.0.0.
The FCA now accepts only UKSEF 2022 v2.0.0 since May 3, 2022, into NSM for all companies opting to use UKSEF for their filing.

All UK-listed companies will stand to gain more with UKSEF and have the option of filing using UKSEF taxonomy with FCA rather than Companies House. UK Department for Business, Energy & Industrial Strategy (BEIS) indicates that UKSEF also complies with the mandatory requirement of filing with the FCA, and hence is a viable alternative to ESEF for firms filing in the UK.

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