HM Revenue & Customs

I'm attaching my accounts and computations to my CT600 return form - What do I need to do to make sure the data is in iXBRL format?

Most companies won't have to take special steps to convert accounts or computations into iXBRL. This will be done automatically by commercially available Final Accounts Production (FAP) or tax preparation software. However, FAP and conversation software users may have to do some manual tagging initially to expand on the automatic tagging provided by the software.

You can find detailed guidance about how and what to tag in iXBRL format on the Corporation Tax online filing and electronic payment webpage