Trend Analysis on Custom Tag Rates in XBRL Exhibits Submitted from 2016 to 2018
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 XBRL exhibits submitted in Forms 10-K and 10-K/A from January 2016 to December 2018. The purpose of the analysis was to analyze trends in filers’ use of custom tags in their XBRL submissions during the last three years.
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 has 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. 
I. TREND ANALYSIS
Graph A: Average Custom Tag Rates by Fiscal Year – Forms 10-K and 10-K/A
 963 of 18,057 forms included in the analysis represent voluntary Inline XBRL filings.
 Release No. 33-9002 (Jan. 30, 2009), 74 FR 6776 (Feb. 10, 2009).
 Our analysis includes custom tags of line item tags and excludes tags that are abstract, text-related, member, domain, and document and entity. For definitions of abstract, member, and domain, see XBRL glossary at https://www.sec.gov/page/osd_xbrlglossary. Document and entity tags are largely related to identification and classification of filers and include, among other things, form type, company name, filer size, and public float.
 17 CFR 232.405(c)(iii).
 See n. 1. at 104-05.
 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.”).
* DERA staff identified “large accelerated filers,” “accelerated filers,” “non-accelerated filers,” and “smaller reporting companies” based on their self-identifications on their Forms 10-K and 10-K/A. Verification of the accuracy of the self-identification is beyond the scope of this analysis.
The trend analysis for Forms 10-K and 10-K/A shows that the average custom tag rates for the surveyed filers declined over the three-year assessment period. With respect to filer subsets, custom tag rates for non-accelerated filers and smaller reporting companies declined over the three-year assessment period, while custom tag rates for large accelerated filers and accelerated filers remained flat. Additionally, the trend analysis shows that while the average custom tag rates for non-accelerated filers declined over the assessment period, those filers had the highest average custom tag rates. By contrast, the smaller reporting companies had the lowest average custom tag rates.
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 trends, issue guidance, or pursue other actions.
For the staff observations DERA staff published on custom tag rates in 2014, see http://www.sec.gov/dera/reportspubs/assessment-custom-tag-rates-xbrl.html. For the staff’s previous trend analyses on custom tags, see section Trends on this page, see https://www.sec.gov/structureddata/osdstaffobsandguide.
DERA staff welcomes your questions and comments. Please feel free to call us at (202) 551-5494 or email us at StructuredData@sec.gov.