The taxonomies (or dictionaries) currently used for filing to HMRC and Companies House are:
The accounts taxonomies include some common components. These cover standard business information, such as company name, activities and similar data, and standard reports such as the Directors’ Report and Auditors’ Report.
The accounts taxonomies are available for download from the XBRL UK website and the CT taxonomy from the Gov.uk website, but we expect them normally to be bundled with conversion software. Taxonomies can only be viewed in suitable software. However, XBRL UK has provided Excel lists of their content, but these provide limited views of the taxonomy. Taxonomies like the FRC accounts taxonomy present a list of tags in the same format as a set of typical accounts, with a profit and loss statement, balance sheet, notes to the accounts as appropriate.
However, because taxonomies have to cover a large range of possible tags, their content is much larger than that of ordinary single company reports.
The labels on tags are similar to those in ordinary accounts, but tend to be longer and more explicit in order to identify them clearly.
The label and position of a tag in a taxonomy will normally identify it unambiguously, but taxonomies also provide subsidiary information, such as debit/credit type and accounting references, which may aid in identification. Taxonomies inevitably present a ‘common denominator’ view of data. Their structure will not necessarily match that of an individual company’s accounts or computations. In some cases, a company may need to use a tag from the taxonomy notes within a primary statement and vice versa.
The taxonomies only provide tags for data items whose appearance in company reporting is reasonably typical or predictable. They do not define tags for every eventuality or for company-specific or unusual line items. Therefore, it is almost inevitable that items will exist in the financial accounts which will have no XBRL tag. This is acceptable to HMRC since these items will still be visible in the human readable web document, which preserves the full format and details of the accounts.
Taxonomies will be updated from time to time, probably on an annual basis, to reflect changes in regulations and feedback from users. Announcements on updated versions and their dates of validity will be published via XBRL websites and other normal channels. Software providers are expected to update their software where necessary to handle the new taxonomies.