Section 40. Valuation of benefits from interests ceasing on death

40. Valuation of benefits from interests ceasing on death.—The value of the benefit accruing or arising from the cesser of an interest ceasing on the death of the deceased shall— (a) if the interest extended to the whole income of the property, be the principal value of that property; and (b) if the interest extended to less than the whole income of the property, be the principal value of an addition to the property equal to the income to which the interest extended.