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HMRC internal manual

COTAX Manual

Case records: maintaining case records: entering contact details in COTAX

It is important that all available telephone numbers and email addresses are entered on to a company record. The CT responsible office and Debt Management and Banking offices can update company telephone numbers and the ‘RLS’ signal.

Telephone numbers or email addresses can be entered using functions:

  • ACNA (Amend Company Name / Address)
  • ACOM (Amend Communication Details).

Where you do not have the functionality to update the COTAX record, you should advise the responsible office.

You cannot enter a communication telephone number using function ACOM without an address being present. If you do not have a communication address but need to add a telephone number, enter the company’s Registered Office address.


  • COM42011 for a list of forms relevant to this subject
  • COM42012 for a list of functions to use in particular situations.