iXBRL stands for inline eXtensible Business Reporting Language. The format combines a readable annual accounts (jaarrekening) with structured XBRL tags in a single xHTML document, so that the file can be processed by both humans and machines. In the Netherlands, iXBRL is becoming mandatory alongside the existing SBR format for KvK filing, and it has been the standard for years for ESEF reporting by listed companies reporting under IFRS.
Key data
For whom: all legal entities that file annual accounts (jaarrekening) with the KvK in the Netherlands, and listed companies on EU-regulated markets reporting under IFRS (ESEF).
Technical core: iXBRL is a W3C/XBRL International standard; the XBRL tags are embedded in xHTML so that a single file is both human-readable and machine-readable.
Legal basis NL: Book 2 BW, Title 9; the SBR Filing Rules (FR-NL) for KvK-filing.
Format: an iXBRL file has the .xhtml extension or is contained within a Report Package (.zip).
Regulator NL (KvK/SBR): Logius manages the SBR infrastructure; KVK receives the filings (deponeringen).
ESEF regulator: ESMA establishes the ESEF taxonomy; in the Netherlands, the AFM provides oversight.
What is XBRL?
XBRL (eXtensible Business Reporting Language) is an open standard for recording financial data in a structured and machine-readable format. In an XBRL instance, financial figures are assigned semantic labels from a taxonomy: “net turnover”, “balance sheet total”, “equity”, and so on.
An XBRL instance is not intended to be read directly by humans. It is an XML file that requires software to interpret, meaning a separate readable document is always necessary alongside the instance.
For KvK filings, the Netherlands has been using XBRL via the SBR channel for years, based on the NL Taxonomy managed by the SBR Program and XBRL Nederland.
What is iXBRL and why is it different?
iXBRL solves the central problem of XBRL: the separation between readability and structure. With iXBRL, the XBRL tags are embedded directly into an xHTML document that looks like a regular annual accounts (jaarrekening) to humans. Open the file in a browser: you see the layout, the tables, and the text. Open the file in an XBRL processor such as Arelle: you see the tagged financial data.
The result is one file with two faces:
A readable annual accounts (jaarrekening) in xHTML, suitable for publication on the website or as an attachment.
A machine-readable XBRL data layer, suitable for automated processing by regulators, investors, and data aggregators.
This makes iXBRL particularly suitable for environments where both disclosure and automated processing are required, such as ESEF and the increasing digitalization requirements of the KvK via SBR.
XBRL versus iXBRL: the core differences
Reference | XBRL (instance document) | iXBRL (Inline XBRL) |
|---|---|---|
File format | XML | xHTML |
Human-readable | No, requires software | Yes, directly in the browser |
Machine-readable | Yes | Yes |
Number of files | Minimum 2 (instance + readable report) | 1 combined file |
Use in NL (Dutch GAAP) | SBR XBRL-instance via Logius/KVK | Option alongside SBR from financial year 2024 |
Use ESEF (IFRS) | Not applicable | Mandatory standard |
Taxonomy NL | NL Taxonomy | NL Taxonomy (at KVK) or ESEF taxonomy (at IFRS) |
Validation tool | Arelle, SBR Filing Rules | Arelle, SBR Filing Rules or ESEF Conformance Suite |
Where do you encounter iXBRL in the Netherlands?
It is important to distinguish between two strictly separate regimes.
KvK filing under Dutch GAAP (SBR)
Micro and small legal entities have been required to file electronically via SBR since financial year 2016. Medium-sized legal entities have been required to do so since financial year 2017. Large legal entities will follow; it is expected that paper filing for large entities may be abolished starting from financial year 2025, but this is a phased and planned trajectory.
Starting from financial year 2024, there is a choice of format for filing with the KvK: the classic SBR format (a separate XBRL instance) or the iXBRL format (a European iXBRL file in xHTML). Legal entities reporting under IFRS or falling under CSRD requirements are mandatory to use the iXBRL format.
The filing takes place via the SBR infrastructure of Logius. Medium-sized and large legal entities must also include an audit opinion (accountantsverklaring), submitted digitally via SBR Assurance.
ESEF reporting under IFRS (listed companies)
ESEF stands for European Single Electronic Format. It is an ESMA requirement that applies to issuers on EU-regulated markets that prepare their consolidated annual accounts (jaarrekening) under IFRS. In the Netherlands, the AFM supervises compliance.
ESEF uses iXBRL based on the ESEF taxonomy, an extension of the IFRS taxonomy. The primary financial statements (profit and loss account, balance sheet, cash flow statement, and changes in equity) have been mandatory to tag since financial year 2020. Block tagging of the notes is mandatory from financial year 2022. Extensions to the ESEF taxonomy must be anchored to the nearest standard IFRS concept. The entity ID in ESEF is the LEI number, not the KvK number.
⚠ Do not confuse ESEF with KvK filing. ESEF applies exclusively to consolidated IFRS annual accounts (jaarrekeningen) of listed companies. KvK filing is for all Dutch legal entities with a publication obligation and works with the NL Taxonomy and Dutch GAAP.
How is an iXBRL file validated?
The most widely used open-source XBRL processor is Arelle, certified by XBRL International. Arelle checks whether the XBRL tags are correctly formulated, whether the concepts match the taxonomy, and whether the calculations are internally consistent.
For KvK filings, the SBR Filing Rules (FR-NL) additionally apply. These rules, published by the SBR Programma and XBRL Nederland, determine which concepts are mandatory and which additional technical requirements apply to the Report Package.
For ESEF, the ESMA ESEF Conformance Suite applies. Software vendors and internal teams can use it to test whether the iXBRL file complies with the ESEF requirements before it is submitted to the AFM or the stock exchange.
Related topics
How do you convert annual accounts (jaarrekening) to XBRL or iXBRL? A step-by-step explanation of the conversion process, from approved PDF document to validated iXBRL file.
Electronic filing: SBR or iXBRL? When do you choose the classic SBR format and when is iXBRL the right choice for your filing with the KvK.
ESEF reporting and iXBRL for IFRS companies Everything about the ESEF obligation for listed companies, the ESEF taxonomy, LEI numbers, and the role of the AFM.
Frequently asked questions
What is the difference between XBRL and iXBRL?
XBRL (eXtensible Business Reporting Language) is a structured XML format that makes financial data machine-readable, but is not directly readable for humans. iXBRL (Inline XBRL) combines the XBRL tags with a readable xHTML document in a single file. With iXBRL, you see a normal annual accounts (jaarrekening) in a browser, while an XBRL processor can simultaneously read the tagged financial data. The main practical difference is that with iXBRL you have one file that meets both requirements, whereas with classic XBRL you need a separate readable report alongside the XBRL instance.
What is the meaning of iXBRL?
iXBRL is the abbreviation for inline eXtensible Business Reporting Language. “Inline” refers to the fact that the XBRL tags are embedded (“inline” placed) within an xHTML document, so that human readability and machine readability are combined into a single file.
What is the full name of iXBRL?
The full name is inline eXtensible Business Reporting Language. The abbreviation iXBRL is also written as IXBRL or Inline XBRL.
Is it mandatory to file annual accounts (jaarstukken) electronically?
Yes. In the Netherlands, electronic filing via SBR is mandatory for micro and small legal entities from financial year 2016, and for medium-sized legal entities from financial year 2017. Large legal entities follow in a phased trajectory. The filing takes place via the SBR infrastructure of Logius to the KvK. Paper filing for large entities may be abolished starting from financial year 2025, but this is a planned and ongoing trajectory.
What file format does an iXBRL file have?
An iXBRL file is an xHTML file (.xhtml or .htm) with embedded XBRL tags, typically bundled in a Report Package: a ZIP archive containing the iXBRL document and associated taxonomy references.
Do I need to use the same taxonomy for ESEF as for the KvK?
No. KvK filing uses the NL Taxonomy (Dutch GAAP, managed by the SBR Program and XBRL Nederland). ESEF uses the ESEF taxonomy, an extension of the IFRS taxonomy managed by ESMA. The two regimes and taxonomies are completely separate.
Doc2iXBRL for iXBRL conversion and validation
Doc2iXBRL is a platform for accountants and finance teams who need to convert approved annual accounts (jaarrekening) (PDF or Word) into a valid iXBRL file. The software automatically suggests XBRL tag mappings based on the NL Taxonomy or the ESEF taxonomy, while the reviewer remains fully in control of the final tags. Built-in Arelle validation and proprietary pre-filing checks verify the iXBRL file before it is submitted, without guaranteeing a KvK or ESMA acceptance outcome.
Book a demoSources
nl.xbrl.org: XBRL Nederland, technical documentation NL Taxonomy and SBR Filing Rules
sbr-nl.nl: SBR Programma, standards and filing rules for electronic deponering
kvk.nl: Chamber of Commerce (Kamer van Koophandel), requirements and processes for filing annual accounts (jaarrekening)
