What is iXBRL and ESEF tagging? A guide for finance and sustainability teams
What XBRL, iXBRL and ESEF are, why annual and sustainability reports are now filed in tagged formats, who does the tagging, and how to find a filing provider.
Regulators increasingly want reports in a form computers can read as well as people. XBRL is the standard way to do this: each number in a report carries a tag that says what it is, for what period, in which currency. Inline XBRL (iXBRL) puts those tags inside the readable report itself, so one file serves both.
ESEF in one paragraph
The European Single Electronic Format (ESEF) requires issuers on EU regulated markets to publish their annual financial reports in XHTML, with the consolidated financial statements tagged in iXBRL. National regulators collect the files. Under the CSRD, sustainability reporting is also to be digitally tagged, using a taxonomy based on the ESRS. Exact timing and national details vary, so check your regulator.
What tagging involves
- Choose the taxonomy. The set of tags for your standard, such as the IFRS taxonomy for financial statements or an ESRS taxonomy for sustainability.
- Map your report. Each figure and some text blocks are matched to the right tag.
- Create the file. The report is built in a valid format, often as a package.
- Validate. Software checks for errors against the taxonomy and regulator rules.
- File. Submit to the regulator or registry.
Tagging mistakes are common, and some regulators reject files with errors, so time and checks matter.
Who does the tagging
- In-house, with tagging software, if you file regularly and have the skills.
- A filing agent or specialist, which suits companies that file once a year or want a second pair of eyes.
- Your reporting software, if it includes tagging. Ask whether it covers the taxonomy you need.
How to choose
Ask about the taxonomies and regulators they support, how they handle changes in taxonomy each year, their validation checks, turnaround before a deadline, and whether they work directly with your auditor.
Find providers
Software: XBRL and iXBRL tagging tools. Services: XBRL and ESEF conversion and tagging services.
UBPartner
XBRL software for regulatory and ESEF reporting.
AMANA
XBRL and ESEF reporting software and consulting.
Datatracks
Regulatory reporting software and services provider offering iXBRL, XBRL and ESEF filing across many jurisdictions.
Workiva
Cloud platform that brings financial and sustainability reporting together, including CSRD reports and digital tagging.
Ordered by verified reviews and relevance. Listings are never ranked by payment. See all 9 providers
Related
This guide is general information, not legal, tax or investment advice. Rules change; check the official sources and talk to an adviser before you rely on it.
Related guides
What assurance providers ask for in a sustainability report
The evidence, documentation and controls an assurance provider typically expects to see when reviewing a sustainability report, and how to prepare before they arrive.
How-to guideHow to prepare your first VSME sustainability report
A practical walkthrough for small and mid-sized companies answering customer and bank requests with a VSME-style report: which module, what data, who owns what, and how to avoid over-reporting.
How-to guideDouble materiality assessment: a step-by-step process
A working process for running a double materiality assessment, from scoping and stakeholder input to scoring, sign-off and documentation, with the evidence an auditor will want to see.