Quick succession relief applies to reduce the tax chargeable on the value transferred on death, in other words the tax chargeable on the aggregate estate. Where it is necessary to apportion the QSR between different parts of the estate, this is normally done by reference to capital values (IHTM 45050).
Andrew dies, leaving an estate worth £400,000 chargeable at an estate rate of 40%. In his will he leaves £60,000 to Bob outright, and settles £50,000 on Bob for life, with remainder to Colin. The residue of his estate passes to his widow.