Enquiries: penalty enquiries
Whenever you contact a taxpayer, or their agent, to clarify or question the reasons why an asset was omitted, or under-valued in the original account, that is an enquiry (IHTM29011). The penalties section (IHTM36000) of this manual tells you when you should seek a penalty.
Imposing a penalty for the late delivery of an account (IHTM29013) does not amount to opening an enquiry. If you then challenge aspects of the late account you will need to open an enquiry at that stage.