IHTM10061 | Investigating the assets on page 6: Cash (box 53)
From HM Revenue & Customs · Inheritance Tax Manual
Any cash that is not held at a bank should be shown in box 53 on the IHT400. This will include
any cash held by the deceased or kept at home or elsewhere such as a safe deposit box
cash held for the deceased by someone else, for example, a stockbroker
travellers cheques
any uncashed cheques made out to the deceased.
Sterling travellers’ cheques should be included at face value. If the travellers’ cheques are in a foreign currency they should be converted into sterling using one of the many currency conversion websites available on the internet.