(1) If the gross estate includes property upon the transfer of which to the decedent a tax was previously and within five (5) years imposed by this state, or property that has been received by the decedent in exchange for property upon which a tax was so imposed, a credit on account of such tax actually so previously paid shall be allowed against the tax imposed with respect to the particular property, but not to exceed the amount of tax imposed with respect to the property on the present transfer.
(2) The credit for previously paid tax computation shall be the lesser of the following: The tax paid in the previous estate multiplied by the result of the total property amount transferred to the present estate divided by the taxable estate of the prior estate; or
(3) The tax due in the present estate multiplied by the result of the total property amount received from the prior estate divided by the taxable estate of the present estate.
(4) The five-year period shall be computed from the date of death of the prior decedent and not from the date of payment of such tax.