26 USC 2523 - Gift to spouse
Where a donor transfers during the calendar year by gift an interest in property to a donee who at the time of the gift is the donors spouse, there shall be allowed as a deduction in computing taxable gifts for the calendar year an amount with respect to such interest equal to its value.
Where, on the lapse of time, on the occurrence of an event or contingency, or on the failure of an event or contingency to occur, such interest transferred to the spouse will terminate or fail, no deduction shall be allowed with respect to such interest
An exercise or release at any time by the donor, either alone or in conjunction with any person, of a power to appoint an interest in property, even though not otherwise a transfer, shall, for purposes of paragraph (1), be considered as a transfer by him. Except as provided in subsection (e), where at the time of the transfer it is impossible to ascertain the particular person or persons who may receive from the donor an interest in property so transferred by him, such interest shall, for purposes of paragraph (1), be considered as transferred to a person other than the donee spouse.
Where the assets out of which, or the proceeds of which, the interest transferred to the donee spouse may be satisfied include a particular asset or assets with respect to which no deduction would be allowed if such asset or assets were transferred from the donor to such spouse, then the value of the interest transferred to such spouse shall, for purposes of subsection (a), be reduced by the aggregate value of such particular assets.
If the interest is transferred to the donee spouse as sole joint tenant with the donor or as tenant by the entirety, the interest of the donor in the property which exists solely by reason of the possibility that the donor may survive the donee spouse, or that there may occur a severance of the tenancy, shall not be considered for purposes of subsection (b) as an interest retained by the donor in himself.
Where the donor transfers an interest in property, if by such transfer his spouse is entitled for life to all of the income from the entire interest, or all the income from a specific portion thereof, payable annually or at more frequent intervals, with power in the donee spouse to appoint the entire interest, or such specific portion (exercisable in favor of such donee spouse, or of the estate of such donee spouse, or in favor of either, whether or not in each case the power is exercisable in favor of others), and with no power in any other person to appoint any part of such interest, or such portion, to any person other than the donee spouse
This subsection shall apply only if, by such transfer, such power in the donee spouse to appoint the interest, or such portion, whether exercisable by will or during life, is exercisable by such spouse alone and in all events. For purposes of this subsection, the term specific portion only includes a portion determined on a fractional or percentage basis.
In the case of qualified terminable interest property
For purposes of this subsection, the term qualified terminable interest property means any property
For purposes of this subsection, rules similar to the rules of clauses (ii), (iii), and (iv) of section 2056 (b)(7)(B) shall apply and the rules of section 2056 (b)(10) shall apply.
An election under this subsection with respect to any property shall be made on or before the date prescribed by section 6075 (b) for filing a gift tax return with respect to the transfer (determined without regard to section 6019 (2)) and shall be made in such manner as the Secretary shall by regulations prescribe.
An election under this subsection, once made, shall be irrevocable.
In the case of any qualified terminable interest property
Subparagraph (A) shall not apply with respect to any property after the donee spouse is treated as having transferred such property under section 2519, or such property is includible in the donee spouses gross estate under section 2044.
In the case of a joint and survivor annuity where only the donor spouse and donee spouse have the right to receive payments before the death of the last spouse to die
An election under subparagraph (B), once made, shall be irrevocable.
If, after the transfer, the donee spouse is the only noncharitable beneficiary (other than the donor) of a qualified charitable remainder trust, subsection (b) shall not apply to the interest in such trust which is transferred to the donee spouse.
Nothing in this section or any other provision of this chapter shall allow the value of any interest in property to be deducted under this chapter more than once with respect to the same donor.
If the spouse of the donor is not a citizen of the United States
This subsection shall not apply to any transfer resulting from the acquisition of rights under a joint and survivor annuity described in subsection (f)(6).