Inheritance tax rules in practice. What this means in practice is that any proportion of the tax-free allowance that was not used when your husband, wife or civil partner died can be transferred to you as the surviving partner for use on your death.nder Estate Duty rules up to that date no transfers could be made tax-free between husband and wife. Estates valued at less than a certain amount (this differed depending on date of death), didn’t attract tax, but estates over this amount had to pay tax on the whole value.