HM Revenue and Customs is warning half a million tax professionals to be ready for a new tax reporting language, in a mass mail out this month.

As of 31 March 2011, accountants will be forced to use a tagged data format known as XBRL.

Mark Holden, Director of HMRC’s Carter Programme, said the changes will affect accounting periods ending after 31 March next year. Agents and businesses need to be thinking about these changes now.

'We’re working closely with software developers, and a number of commercial products will be available to support the iXBRL standard from November 2009, with more to follow,' he said.

`This will mean the majority of companies who wish to familiarise themselves with filing online before it becomes compulsory will have the opportunity to do so.'