Valuation of benefits or perquisites treated as income when received by a representative assessee or on beneficiary's behalf. Insertion treats the value of any benefit or perquisite obtained by a representative assessee, or by a person for whose benefit income is receivable by that representative (the beneficiary), and any sum paid by the representative in respect of an obligation that would otherwise be payable by the beneficiary, as falling within the taxable characterization for income-tax purposes.