If only things were that straightforward ....
HMRC have been banging on about XBRL (not inline XBRL) for some time, but it was not until approximately 12 months ago that they decided to use the proposed (at the time) inline XBRL standard - sending people who might have started something in standard XBRL back to the drawing board.
As for Inline XBRL - it was only approved as a standard in April 2010 and ratified in May - so the ink is hardly dry.
And on top of this currently HMRC don't even comply with the published standard yet - they are still on an earlier 'candidate release' that has issues accepting those documents that do use the official standard.
Even though XBRL is used world-wide and has been for many years, the UK has decided to go down the inline XBRL route, and as such the world's first inline XBRL 'pilot' is to be undertaken by ~2 million UK corporate tax filers starting from April ...
Why do HMRC want inline XBRL ? Well inline embeds the XBRL into an HTML document that human beings can read, as opposed to usual XBRL with is a variant of XML with knobs on.
Because HMRC don't have any software that their tax inspectors can use that makes sense of an XBRL document, and are not prepared to spend any money to develop one, it is much cheaper for them to mandate that the submitters do it for them.
The upshot of this is now Companies House will also move to inline XBRL for the filing of statutory accounts, having so far accepted voluntary XBRL filings - so all change yet again - the only positive here being that the same document should be acceptable by both HMRC and Companies House. The intention is that this will be mandatory from April 2013, legislation permitting - hopefully the software companies are listening a bit more intently this time.
The real short-term goal, as pointed out, is to do away with the paper and force electronic submissions, as this removes government post rooms (> 5 million documents per annum for Comapnies House even though electronic submission is well over the 50% mark) plus the miles of shelves to keep them on.
But be prepared for it to all change again when companies are forced to adopt IFRS reporting.
As for Sage filing their accounts, well Sage are so big that they cannot use their own software, but use a Hyperion consolidation system to get their figures, So unfortunately no "eat your own dog-food" here.
Anonymous as I work for an XBRL provider ... and yes it is harder than it needs to be