An agent code (sometimes know as an agent reference number), identifies you as an agent with HM Revenue and Customs (HMRC) for some taxes - for example Self Assessment, Corporation Tax or PAYE for employers. An agent code is specific to you as an agent and that HMRC business area.
Enter the HMRC agent code that relates to the type of issue you're escalating in this form, if appropriate. For example, if you've a problem with your client's Self Assessment tax return, enter your Self Assessment agent code in this box. Follow the link below to read more about agent codes and client authorisations on the GOV.UK website.