The legislation, which came into force on 1 January 2010, means that it is compulsory for companies to send their Company Tax Return online using iXBRL for accounts and computations.
Effective on or before 1 April 2011 for any accounting period ending after 31 March 2011, UK company tax returns must be filed online to HMRC in Extensible Markup Language (XML) with the accompanying statutory accounts and tax computations in the inline variant of the eXtensible Business Reporting Language (XBRL) format known as inline XBRL (iXBRL)
These filings will need to adhere to UK GAAP and IFRS Taxonomies. HMRC has looked at the full library of possible tags and has now published a minimum tagging list for UK GAAP accounts and UK IFRS accounts.

XBRL describes this information using `tags` that work like bar codes, and it defines each of these using a number of dictionaries called `taxonomies`. Any organisation or individual that wants to apply, read and process these tags requires software that has been specially designed or modified for this purpose; but with the right software, XBRL can make it easier to handle different items of financial information, in the same way as bar codes make it easier to handle assets or manage the supply chain. With the Inline eXtensible Business Reporting Language, HM Revenue & Customs has overcome this. iXBRL combines the structured, machine readable data of XBRL with a rendering that can be read by the human eye, so people can open iXBRL files, using a web browser, and see the original content and format of a document, whilst compatible software can automatically read and process the tagged XBRL data.

The eXtensible Markup Language (XML) was created so that richly structured documents could be used over the web. There is no pre-defined tag set for XML, because it is a `meta-language` that provides a facility to define tags and the structural relationships between them and to describe and analyse markup languages u2013 such as XBRL.
XBRL was designed to make it easier for computer software to automatically communicate, exchange, read, process and analyse financial information (as data), so it cannot easily be `read` by people and XBRL tagged files cannot easily be used to reproduce a financial source document in its original format.
HMRC has overcome this by requesting files in inline XBRL (iXBRL). As it combines HTML (a text-based language designed to display data) and XBRL tags, people can open iXBRL files (using a web browser) and see the original content and format of a document, while the tagged XBRL data can be stripped out and automatically processed by software.

The definitions for XBRL tags are to be found in special dictionaries called taxonomies. There are a number of taxonomies available and under development, because different taxonomies are (typically) required for different financial reporting processes, jurisdictions and statutory financial reporting requirements u2013 some individual organisations may even define their own extension taxonomies for management reporting purposes. These taxonomies have been developed by various groups of stakeholders. You can learn more about them and everything else related to XBRL, by visiting the websites of the Consortia XBRL International (www.xbrl.org) or XBRL UK (www.xbrl.org/uk).