You must usually make any changes (‘amendments’) within 12 months of the filing deadline.
- log in to HM Revenue and Customs (HMRC) online services to amend your Company Tax Return
- use commercial software
- send a paper return or write to your company’s Corporation Tax office
Check recent tax forms or letters from HMRC for the Corporation Tax office address or call the helpline.
HMRC may charge you a penalty for errors.
HMRC can make a compliance check to check for errors in your Company Tax Return.