Custom Tag Rates in IFRS XBRL Exhibits Submitted in 2017 and U.S. GAAP XBRL Exhibits Submitted in 2011 and 2017
The staff in the Commission’s Division of Economic and Risk Analysis (DERA) recently analyzed eXtensible Business Reporting Language (XBRL) exhibits submitted by issuers complying with the 2009 Interactive Data rules to file financial statement information in an XBRL format. Our analysis covered:  Our analysis covered:
- Custom tags in the primary financial statements of XBRL exhibits submitted for Forms 20-F, 20-F/A, 40-F and 40-F/A reporting in International Financial Reporting Standards (IFRS) as issued by the International Accounting Standards Board (IASB)  for 2017 and
- Custom tags in the primary financial statements of XBRL exhibits submitted for Forms 10-K and 10-K/A reporting in U.S. Generally Accepted Accounting Principles (GAAP) for 2011 and 2017.
The custom tags in our analysis covered all non-member and non-abstract elements. The purpose of the analysis was to discern whether IFRS filers, in their first year of required XBRL submissions, were being consistent in their use of custom tags with other filers, or whether their use of custom tags diverged from other filers. In our analysis, the custom tag rate of IFRS filers is higher than that of other filers. IFRS filers had a custom tag rate of 16% in 2017. By comparison, U.S. GAAP filers had a custom tag rate of 9% in 2017. Or as another comparison, in the first year of full compliance by all U.S. GAAP filers, U.S. GAAP filers had a custom tag rate of 11% in 2011.
The Commission’s rules allow filers to create custom tags when the standard taxonomy does not provide a tag for the necessary financial element. While this customization accommodates unique circumstances in a filer’s particular disclosure, the Commission acknowledged that the use of unnecessary customized tags could potentially reduce the comparability of inter-company data.  Thus, the Commission’s rules specify the limited circumstances under which a filer may create custom tags. 
DERA staff intends to continue to review filers’ use of XBRL in their submissions to the Commission. Depending on the results of those efforts, DERA staff may share additional analysis, issue guidance, or pursue other actions.
For the staff observations DERA staff published on custom tag rates in 2014, see https://www.sec.gov/dera/reportspubs/assessment-custom-tag-rates-xbrl.html. For previous trend analyses on custom tag rates, see https://www.sec.gov/structureddata/trends and https://www.sec.gov/structureddata/trends_2017.
DERA staff welcomes your questions and comments. Please feel free to call us at (202) 551-5494 or email us at StructuredData@sec.gov.
 Release No. 33-9002 (Jan. 30, 2009), 74 FR 6776 (Feb. 10, 2009) (“2009 Rule”).
 See 2009 Rule at 104-105.
 See 17 CFR 232.405(c)(iii)(B) (“An electronic filer must create and use a new special element if and only if an appropriate tag does not exist in the standard list of tags for reasons other than or in addition to an inappropriate standard label.”).