In the case where a person has acquired property located outside the area where this Act is enforced by inheritance or bequest (including a gift prescribed in Article 21-2, paragraph (4); the same applies hereinafter in this Article), if tax equivalent to inheritance tax has been imposed on that property under the laws and regulations of that place, for the person who has acquired that property, the amount obtained by deducting the amount equivalent to the amount of tax so imposed from the amount calculated pursuant to Article 15 through the preceding Article is the amount of inheritance tax to be paid; provided, however, that where the amount to be deducted exceeds the amount calculated by multiplying the amount calculated for that person pursuant to those provisions by the proportion that the value of that property represents of the portion of the value of the property acquired by that inheritance or bequest that was included in the basis for calculating the taxable value, that deduction is not made as to the excess amount.