One of our payroll clients requires their P35 to be amended however when I have logged into HMRC they are not on our authorised or unauthorised client list. Do I need to issue them with a 64-8 and then apply for an authorisation code for online filing? Also, as they don't appear when I log in does this mean I won't be able to access their P35 to amend? It seemed to submit ok through Sage payroll at year end.