IHTM46024 - Calculating the RNRB: terms used: the 'default allowance'
The legislation refers to a person’s ‘default allowance�. This is the maximum potential value of the residence nil rate band for that estate before applying the taper threshold (IHTM46023). It is the total of:
(i) the residential enhancement at the person’s death (IHTM46022), and
(ii) the person’s ‘brought forward allowance� (IHTM46040).
However, if the value of the estate exceeds the taper threshold the ‘default allowance� is reduced to become the ‘adjusted allowance�  (IHTM46025).