(a) A tax is imposed upon every generation-skipping transfer in an amount equal to the amount allowable as a credit for state inheritance taxes under 26 U.S.C. § 2604.
(b) If any of the property transferred is real property located in another state or is tangible personal property having an actual situs in another state that requires the payment of a tax for which credit is received against the federal generation-skipping transfer tax, any tax due pursuant to subsection (a) shall be reduced by an amount that bears the same ratio to the total state tax credit allowable for federal generation-skipping transfer tax purposes as the value of such property taxable in such other state bears to the value of the gross generation-skipping transfer for federal generation-skipping transfer tax purposes.