This part of GOV.UK is being rebuilt – find out what beta means

HMRC internal manual

Inheritance Tax Manual

Assessing: CTDs: if the taxpayer has lost the CTD

When the taxpayer states that they have not received or cannot find their CTD, refer the matter to CTD Team with a copy of the taxpayer’s letter or, if no letter is available, full details of the taxpayer or agent dealing with the case.