The amount of tax determined under section 7442a of this chapter on an estate which qualifies for installment payment of estate taxes under 26 U.S.C. § 6166, and in which the closely-held business is the business of farming in Vermont, shall be reduced by the percentage which the value of the closely-held farm business, as determined for federal estate tax purposes, bears to the value of the federal adjusted gross estate. (Added 2001, No. 140 (Adj. Sess.), § 21, eff. June 21, 2002; amended 2003, No. 70 (Adj. Sess.), § 51, eff. March 1, 2004.)