Rev. Rul. 56-439

Where a gift is made in trust the terms of which provide that the trustee is to distribute any part of all of the income or principal of the trust to or among the spouse of the donor and any lineal descendants and/or spouses of lineal descendants of the donor at such times and in such proportions and amounts as he in his sole discretion shall determine, the value of the right to receive the income or principal to be distributed to the wife is not susceptible of determination. See Rev. Rul. 55-303, C.B. 1955-1, 471. Under such circumstances, the gift to the wife is not severable from the gifts to the other beneficiaries. Accordingly, it is held that the gift may not to any extent be considered as made one-half by the donor and one-half by his spouse within the meaning of section 2513 of the Internal Revenue Code of 1954.