XBRL (eXtensible Business Reporting Language)

XBRL (eXtensible Business Reporting Language) is an open, XML-based standard for the electronic exchange of financial and business information. It enables machine processing, comparison and analysis of financial data without manual preparation.

• Taxonomies: Structured data dictionaries defining balance sheet, P&L and note items in machine-readable form
• Main users: Securities regulators (SEC, ESMA), tax authorities, central banks, banking supervisors (EBA)
• EU mandate: European Single Electronic Format (ESEF) for listed companies from 2020/2021
• iXBRL: Inline XBRL combines machine-readable XBRL tags with human-readable HTML

XBRL was conceived by American CPA Charles Hoffman in 1998 and first specified as XFRML (eXtensible Financial Reporting Markup Language) in 1999. In April 2000, the project was renamed to XBRL when its scope was broadened beyond financial reporting. The XBRL project was launched under AICPA (American Institute of Certified Public Accountants) leadership in 2000, and XBRL International was established as a global consortium. The first XBRL specification (version 1.0) was released in July 2000. The SEC (US securities regulator) mandated XBRL reporting for listed companies from 2009.

In the EU, XBRL was made mandatory through the Transparency Directive and in particular through Commission Delegated Regulation (EU) 2019/815 (the ESEF Regulation). Companies whose securities are listed on EU-regulated markets must file annual reports in iXBRL format from the 2020 financial year. Due to the COVID-19 pandemic, Delegated Regulation (EU) 2020/1989 allowed member states to postpone the ESEF obligation by one year (to financial years starting 1 January 2021), an option exercised by many member states. The EBA uses XBRL for supervisory reporting (COREP, FINREP).

XBRL is used in various regulatory contexts:

• ESEF (EU): Annual financial reports of companies listed on EU-regulated markets
• EBA XBRL: Supervisory reporting of banks and investment firms (COREP, FINREP)
• ECB: AnaCredit (Analytical Credit Datasets) — granular credit data collection
• SEC (USA): 10-K, 10-Q and other mandatory filings
• Tax authorities: Tax returns in XBRL (e.g. Netherlands, Denmark, Belgium)
• Statistics: Reporting to central banks and statistical authorities

• Tagging of financial data with XBRL elements according to the applicable taxonomy (e.g. IFRS taxonomy, EBA taxonomy)
• For ESEF: iXBRL format; filing via national official mechanism (OAM)
• Mandatory tagging for primary financial statement components; extended tagging for notes disclosures
• Validation against taxonomy schema and validation rules
• Annual adjustment to updated taxonomy versions

3 corrections:
- key_dates: ESEF regulation incorrectly called 'EU Regulation' instead of 'Delegated Regulation'
- History: XBRL was still called XFRML in 1999, not XBRL
- effective_date 1999-01-01 is imprecise — XBRL 1.0 was released July 2000
4 updates:
- key_dates: Inline XBRL (iXBRL) specification missing — central to ESEF understanding
- History/key_dates: COVID-19 postponement of ESEF obligation missing
- key_dates: XBRL 2.1 specification (2003) missing — still the current main version
- last_amended 2022-01-01 is outdated — ESEF taxonomy has been updated multiple times since
3 clarifications.