XBRL filing for all UK companies?

The Computing newspaper and its sister publication Accountancy Age are highlighting the change in Corporation Tax filing regulations that Her Majesty's Revenue and Customs (HMRC) is introducing with effect from 01 April 2011. I've bookmarked some relevant articles here on delicious.com.

The new regulations will affect all firms, and those that file using reporting or accounting package software will need to update and maintain their software to produce returns in the required XML and iXBRL formats.

Most small companies and organisations will be able to use the free HMRC Corporation Tax Online Service to file a Company Tax Return. This can be used by companies or organisations that file a Company Tax Return form (CT600), supporting documentation, and (if necessary) any of these supplementary pages:

CT600A (Loans to participators by close companies)

CT600C (Group and consortium) - parts one and two

CT600J (Disclosure of tax avoidance schemes supplementary pages)

Supporting documents can be supplied in Acrobat (PDF) format.

You can see a demonstration here on the HMRC site.

However, it's not clear from the information on the HMRC site whether PDF format can be used by companies that have to submit the other CT600 supplementary pages:

CT600B - Controlled Foreign Companies (an interest of 25% or more in a foreign company controlled from the UK)

CT600D (2006) - Insurance: company involved in overseas life assurance business (OLAB)

CT600E - Charity and Community Amateur Sports Clubs (CASCs)

CT600F - Tonnage Tax

CT600G - Corporate Venturing Scheme

CT600I - Supplementary charge in respect of ring fence trades

There's clearly a cost of change in all of this. The HMRC online filing service looks clear and straightforward, and it should present little problem either for small businesses or for small accounting firms that submit returns on behalf of their clients. However, new methods will have to be learnt, registrations made, and experience gained, in order for this to work efficiently. Larger companies, or small companies with complex affairs, may well face more serious change costs, including the updating of accounting or reporting software packages, and the introduction of new processes and accounting treatments.

All in all - if you're not sure, the time to consult your accountant has come!

(Disclaimer: I'm not an accountant, but a small business owner with an interest in technology.)