Both Estate Duty (deaths before 13 March 1975) and Capital Transfer Tax (deaths between 13 March 1975 and 17 March 1986), while having tiered rates at which duty or tax was payable, had amounts under which no duty or tax was due. This sum will be the equivalent of the nil rate band for calculating the transferable nil rate band available on the death of a spouse whose estate was subject to either Capital Transfer Tax or Estate Duty. The nil rate band in such cases is defined in FA08/Sch4/Para10.