HMRC expect that all CT600 returns due after 31 March 2011 will be submitted online, and along with attachments such as accounts and computations using the XBRL format. Customers using commercial XBRL software will not have to be concerned about the attachment or tagging process. However, HMRC has produced guidance for customers who will not be using commercial XBRL software.
XBRL stands for Extensible Business Reporting Language, which is an international standard designed for business financial reporting. The guidance note produced by HMRC outlines when and how to embed XBRL tags onto accounts and computations, details on using excel / word conversions for XBRL and details on the expected rise in the Out-sourced XBRL tagging market.
Full information is available here