HMRC guidelines state “The address fields on the CT600 form should only be completed if the address has changed from that shown on the notice to file. In fact, each time the address fields are completed, the return appears on a manual work list within the relevant HMRC department. We believe that some customers may be completing the address field with the same information shown on the CT603 causing an unnecessary delay in fully processing their return. So, in short, only complete the company address fields if it is different to that shown on the CT603 notice to file.