Who extends the extensible?

Purpose - The purpose of this paper is to investigate the extent to which Chinese firms voluntarily extend the standard XBRL taxonomy to disclose more detailed financial information; and second, to identify and test corporate governance factors that may be associated with voluntary taxonomy extensions in eXtensible Business Reporting Language (XBRL)‐based reporting. Design/methodology/approach - Using a sample of 114 firms that are listed on the Shanghai Stock Exchanges, the authors compared their XBRL‐based financial reports of 2008 and 2009 with the standard XBRL taxonomy. Multiple regression tests were performed to examine the effects of corporate governance factors and firm characteristics on XBRL taxonomy extensions. Findings - The results indicate a high level of voluntary taxonomy extension in Chinese firms' XBRL reports. The extent of such extension is associated with the percentage of independent directors, combined CEO/chair of the board position, and firm size. It is also associated with audit firm size, in that companies audited by Big Four firms tend to have lower level of taxonomy extension. However, the direction of the result is opposite to what the authors expected. Research limitations/implications - This paper highlights the effects of corporate governance factors on Chinese firms' decisions to extend XBRL standard taxonomy and, in doing so, to disclose more financial information. Future research may consider using longitudinal data and alternative corporate governance factors to validate and extend the results. Originality/value - It is an unanswered question as to whether and why firms extend standard XBRL taxonomies and disclose additional voluntary information. This paper fills the gap by investigating this issue in the context of the Chinese capital market.