Companies must file annual financial statements and specified reports in XBRL using approved taxonomies for specified thresholds. Specified companies must file annual financial statements and prescribed documents in XBRL using Central Government-approved taxonomies in e Form AOC 4 XBRL for financial years commencing on or after 1 April 2014; covered classes include listed companies (and Indian subsidiaries), companies with paid up capital Rs. 5 crore, turnover Rs. 100 crore, and those previously under the 2011 rules, with exemptions for banking, insurance, power and NBFCs. Cost audit reports under section 148(6) must be filed in e Form CRA 4 using the prescribed XBRL taxonomy. The AOC 4 XBRL form prescribes required fields, attachments, certification and digital signature requirements.