Detailed Footnote Tagging explained

Detailed footnote (DFN) tagging refers to creating XBRL codes for all quantitative (and some qualitative) facts in footnotes instead of creating one overarching code for the footnote.  This allows investor community to drill down to details in foot notes and gain a greater insight into the qualitative aspects of disclosure.  The fact can be a monetary value, percentage item, a number or a period.  Management Disclosure & Analysis (MD&A) is excluded from tagging per SEC rules.  DFN is applicable for companies filing their XBRL returns from second year onwards.

DFN applicability chart follows:

Year 2009 Tier 1/ Wave 1 Large Accelerated Filers
Year 2010 Tier 2/ Wave 2 Accelerated Filers
Year 2011 Tier 3/ Wave 3 Small Reporting Companies
Year 2012 All documents that require XBRL tagging should  have details tagged


DFN tagging can be broadly classified into 4 levels:

Level 1 tagging:

This includes tagging every number in the face financial statements such as Balance Sheet, Income Statement, Cash Flows, Equity Statement and Comprehensive Income.  In addition, it is mandatory that every footnote be tagged as a block of information.  Tagging refers to associating the source fact with a matching element from the US GAAP taxonomy.  Companies can create custom elements and definitions if there are no matching concepts present in the US GAAP taxonomy.

Level 2 tagging:

Here, every policy is tagged as a text block. Example:

  • Earnings per share calculation policy can be tagged with “us-gaap_EarningsPerSharePolicyTextBlock”
  • Recent accounting pronouncement can be tagged with


Level 3 tagging:

This includes tagging tables within the footnote as a block of information.  There can be multiple tables within a footnote that are tagged with different taxonomy elements.   Split tables can be merged as one and can be tagged with one Level 3 taxonomy element.  Example: If Earnings per share tables are provided in two separate tables for different years in the same footnote, they can be merged and tagged with one table text block element.

Level 4 tagging:

Here, every fact within a footnote should be tagged.  These facts can be monetary or percentage item type or date type.  These facts can be part of the table or can be a separate fact within the paragraph information in the footnote.  Numbers represented in words should also be tagged. Example: Words such as “Three”, “Five years”, “Fifty operating units” etc., should be tagged as an independent fact with matching taxonomy element from the taxonomy.  SEC rendering can be different for XBRL and HTML outputsdue to these facts.

The DFN process is very lengthy and intensive.  We, therefore, suggest our clients to start the roll forward process atleast 30 days prior to filing deadline. At DataTracks, we assist our clients with their iXBRL conversion and also accommodate last minute requests within a few hours prior to filing deadline.