For purposes of paragraph (1)(B), the term adjusted taxable gifts means the total amount of the taxable gifts (within the meaning of section 2503) made by the decedent after December 31, 1976, other than gifts which are includible in the gross estate of the decedent.
any tax payable by the spouse under chapter 12 on such gift (as determined under section 2012 (d)) shall be treated as a tax payable with respect to a gift made by the decedent.
such gift shall not be included in the adjusted taxable gifts of the decedent for purposes of subsection (b)(1)(B), and the aggregate amount determined under subsection (b)(2) shall be reduced by the amount (if any) determined under subsection (d) which was treated as a tax payable by the decedents spouse with respect to such gift.
the value thereof shall, for purposes of computing the tax under this chapter, be the value as finally determined for purposes of chapter 12.
For purposes of subparagraph (A), the value of an item shall be treated as shown on a return if the item is disclosed in the return, or in a statement attached to the return, in a manner adequate to apprise the Secretary of the nature of such item.