IHTM26126 | Step 4 - grossing up: other property which bears its own tax
From HM Revenue & Customs · Inheritance Tax Manual
The following other property taxable on the death bears its own tax
joint property () passing by survivorship ()
nominated property ()
property taxable as a gift with reservation (GWR) (IHTM14025) under , and
any other property which does not vest in the deceased’s personal representatives ()