By Max Clarke

HM Revenue & Customs (HMRC) has issued an urgent alert about important changes to Corporation Tax (CT) coming in this April.

The changes will require all company tax returns sent in from April 2011 to be filed online, for accounting periods ending after 31 March 2010, in a specified data format (known as Inline XBRL or iXBRL). CT payments must also be made electronically from April 2011.

As well as limited companies, the changes will affect other organisations that pay corporation tax, including clubs, societies, associations, co-operatives, charities and other unincorporated bodies.

Companies will be able to file online either through commercially available software or by using HMRC’s own CT filing software, which is aimed at companies with less complex tax affairs. A wide range of commercial software is already available, with more coming soon. For more information, click here.

To sign up for Corporation Tax online filing visit and then click “Register for Corporation Tax Online” where you can register. These pages also have lots of information on the changes.

New joint filing service:

HMRC and Companies House have successfully launched a new joint filing service for company accounts.

The new service means that companies with relatively straightforward financial affairs, or their agents, can send their accounts in iXBRL format to HMRC as part of their Company Tax Return, and also send these accounts, or an abbreviated version, to Companies House.

Before you can use this service, you need to have registered for HMRC Online Services and enrolled for Corporation Tax Online. You then use HMRC's Corporation Tax online filing software to submit your accounts to both organisations using a template. For more information, visit HMRC Online.