(a) Except as otherwise provided in subsection (c), the following rules apply:

(1) To the extent that a provision of a decedent's will expressly and unambiguously directs the apportionment of an estate tax, the tax must be apportioned accordingly.

(2) Any portion of an estate tax not apportioned pursuant to paragraph (1) must be apportioned in accordance with any provision of a revocable trust of which the decedent was the settlor which expressly and unambiguously directs the apportionment of an estate tax. If conflicting apportionment provisions appear in two or more revocable trust instruments, the provision in the most recently dated instrument prevails. For purposes of this paragraph:

(A) a trust is revocable if it was revocable immediately after the trust instrument was executed, even if the trust subsequently becomes irrevocable; and

(B) the date of an amendment to a revocable trust instrument is the date of the amended instrument only if the amendment contains an apportionment provision.

(3) If any portion of an estate tax is not apportioned pursuant to paragraph (1) or (2), and a provision in any other dispositive instrument expressly and unambiguously directs that any interest in the property disposed of by the instrument is or is not to be applied to the payment of the estate tax attributable to the interest disposed of by the instrument, the provision controls the apportionment of the tax to that interest.

(b) Subject to subsection (c), and unless the decedent expressly and unambiguously directs the contrary, the following rules apply:

(1) If an apportionment provision directs that a person receiving an interest in property under an instrument is to be exonerated from the responsibility to pay an estate tax that would otherwise be apportioned to the interest, the tax attributable to the exonerated interest must be apportioned ratably among the other persons receiving interests in the apportionable estate that are not exonerated from apportionment of the tax.

(A) Unless the decedent expressly and unambiguously directs to the contrary, a person receiving objects of personal use or ornament, including, but not limited to, wearing apparel, jewelry, books, pictures, art objects, sports equipment, hobby equipment, collections, automobiles, watercrafts, airplanes, household furniture and furnishings, by specific gifts or specific bequests pursuant to the provisions of a will or a revocable trust or by right of survivorship, is exonerated under this paragraph, up to a maximum of $100,000 of the interest received by the person, from the responsibility to pay the estate tax that would otherwise be apportioned with respect to the interests. All interests received by the person in property in excess of $100,000 shall not be exonerated under this subparagraph.

(B) Unless the decedent expressly and unambiguously directs to the contrary, a person receiving gifts or bequests of specific sums of money pursuant to the provisions of a will or a revocable trust that do not in the aggregate exceed $25,000 is exonerated under this paragraph from the responsibility to pay the estate tax that would otherwise be apportioned to the gifts or bequests. If the aggregate amount of the gifts or bequests to a person exceeds $25,000, none of the gifts or bequests to the person shall be exonerated under this subparagraph.

(2) If an apportionment provision directs that an estate tax is to be apportioned to an interest in property a portion of which qualifies for a marital or charitable deduction, the estate tax must first be apportioned ratably among the holders of the portion that does not qualify for a marital or charitable deduction and then apportioned ratably among the holders of the deductible portion to the extent that the value of the nondeductible portion is insufficient.

(3) Except as otherwise provided in paragraph (4), if an apportionment provision directs that an estate tax be apportioned to property in which one or more time-limited interests exist, other than interests in specified property under Section 40-15B-7, the tax must be apportioned to the principal of that property, regardless of the deductibility of some of the interests in that property.

(4) If an apportionment provision directs that an estate tax is to be apportioned to the holders of interests in property in which one or more time-limited interests exist and a charity has an interest that otherwise qualifies for an estate tax charitable deduction, the tax must first be apportioned, to the extent feasible, to interests in property that have not been distributed to the persons entitled to receive the interests.

(c) A provision that apportions an estate tax is ineffective to the extent that it increases the tax apportioned to a person having an interest in the gross estate over which the decedent had no power to transfer immediately before the decedent executed the instrument in which the apportionment direction was made. For purposes of this subsection, a testamentary power of appointment is a power to transfer the property that is subject to the power.