For allowance of the deduction, it is sufficient if either of these conditions is satisfied. Thus, in a case where the entire decrease in Federal estate tax inures to the benefit of a charitable transferee, the deduction is allowable even though the Federal estate tax is not equitably apportioned among all the transferees of property included in the decedent's gross estate. Similarly, if the Federal estate tax is equitably apportioned among all the transferees of property included in the decedent's gross estate, the deduction is allowable even though a noncharitable transferee receives some benefit from the allowance of the deduction.
26 C.F.R. §20.2053-10