(1) If a decedent dies leaving a will that was executed or a trust that was created before September 12, 1981, which will or trust contains a formula expressly providing that the decedent's spouse or a qualifying trust is to receive the maximum amount of property qualifying for the marital deduction allowable by federal law, such formula provision shall be construed as referring to the amount of property which, after utilization of the credits available to the decedent's estate, produces the least possible federal estate tax and is eligible for the marital deduction as allowed under the federal "Internal Revenue Code", as amended by section 403 (a) of the federal "Economic Recovery Tax Act of 1981", P. L. No. 97-34, in effect at the time of the decedent's death; except that such construction shall not be made if its effect is to reduce the amount of property passing to the surviving spouse or a qualifying trust. Such construction shall only be made if the following requirements are met:

(a) The decedent died after December 31, 1988;

(b) The formula referred to in this subsection (1) was not amended to refer specifically to an unlimited marital deduction under federal law at any time after September 12, 1981, and before the death of the decedent;

(c) The will or trust contains a devise to, or is in trust for the benefit of, the decedent's spouse which qualifies for a marital deduction pursuant to section 2056 of the federal "Internal Revenue Code of 1986", 26 U.S.C. sec. 2056, as amended;

(d) There is no finding by the court having jurisdiction over the decedent's estate that the decedent intended to refer to the maximum marital deduction of the internal revenue code in effect at the time that the will or trust was drafted; and

(e) All distributions in satisfaction of the surviving spouse's share of the estate or the qualifying trust for the surviving spouse have not been completed.

(2) For the purposes of this section:

(a) "Amount" includes a fractional, pecuniary, or residual amount.

(b) "Optimum marital deduction formula" means any formula in a will or trust that provides that the decedent's spouse or a qualifying trust is to receive the maximum amount of property that qualifies for the estate tax marital deduction allowable by federal law that produces the least possible or no federal estate tax. A formula subject to construction under subsection (1) of this section is, as construed by subsection (1) of this section, an optimum marital deduction formula.

(c) "Qualifying trust" means any trust for the benefit of the decedent's spouse which qualifies for the marital deduction allowed under section 2056 of the federal "Internal Revenue Code of 1986", 26 U.S.C. sec. 2056, as amended.

(3) In the case of an optimum marital deduction formula that contains a general reference to federal estate tax credits or otherwise requires the state death tax credit to be taken into account without a specific reference to such tax credit, the decedent is presumed to have intended that such tax credit be taken into account to reduce the amount that the decedent's spouse or a qualifying trust is to receive, only to the extent that the overall estate tax burden on the decedent's estate is not thereby increased. However, if a preponderance of the evidence shows that the decedent intended to increase the overall estate tax burden on the estate, the state death tax credit shall be taken into account fully for the purposes of reducing the amount that the decedent's spouse or a qualifying trust is to receive. Any formula subject to construction under subsection (1) of this section is subject to the presumption set forth in this subsection (3).

(4) In the case of an optimum marital deduction formula that specifically requires the state death tax credit to be taken into account and does not contain any words limiting the extent to which such credit shall be taken into account, the decedent is presumed to have intended that such credit be taken into account fully for the purpose of reducing the amount that the decedent's spouse or a qualifying trust is to receive, notwithstanding any resulting increase in the overall estate tax burden on the estate.

(5) Subsections (3) and (4) of this section apply with respect to any decedent who dies after December 31, 1988, unless all distributions in satisfaction of the surviving spouse's share of the estate or the qualifying trust for the surviving spouse are completed by July 1, 1994.