Companies must self-assess their corporation tax liabilities by completing a corporation tax return and submitting it to HM Revenue & Customs (HMRC). They must send in full statutory accounts and corporation tax computations with the return. Since 1 April 2011, all companies have had to file their Company Tax Return online.
Companies normally have to file their return within 12 months of the end of the accounting period. Unless HMRC makes enquiries into the return, the company’s assessment is usually treated as final 12 months after the filing deadline. Companies can amend a corporation tax return any time up to a year after the filing deadline.
HMRC charges penalties for late tax returns. The amount of the penalty depends on how late the return is and whether lateness is habitual, but it is at least £100.