IHTM19040 | Procedures: types of debt reported on form IHT416
From HM Revenue & Customs · Inheritance Tax Manual
Debts due to the deceased and secured by mortgage. These could include any money lent by the deceased to someone, which was secured by a mortgage (IHTM04029) that had not been repaid before they died.
money that the deceased had lent personally to someone else that had not been repaid at the date of death
money linked to a life insurance policy held in trust, and lent to the trustees (IHTM20501)
money for which the deceased held a promissory note.
money for which the deceased held an ‘IOU’
money owing to the deceased from a director’s loan account or current account with a company.