"XBRL: You can't ignore it anymore." So we declared in December 2006. Turns out you could afford to ignore it then, but no longer. Last month the Securities and Exchange Commission issued the final rule that spells out XBRL deadlines.
The 500 largest public companies must start to file their financial results using the interactive data-tagging language known as XBRL this year. The effective date of the new rule is April 13, which means that most initial filings will involve quarterly results for fiscal periods ending on or after June 15. For example, for calendar-year companies, the rule will first apply to Form 10-Qs dated June 30, 2009.
By 2010, all so-called accelerated filers, amounting to about 1,800 public companies, must comply with the new rule, and by 2011 all public companies must be on board.
Companies will have to use XBRL for the three primary financial statements as well as for footnotes, which can be presented in a "block" format in the first year but must be in a more detailed format in subsequent years.
Companies will be allowed to file their first XBRL-coded submissions 30 days after they conduct a more traditional filing on the SEC's EDGAR database system. But all subsequent financial results must be filed on EDGAR and with XBRL tagging at the same time.
You can't say you weren't warned.