In case that the property given by the taxpayer to the spouse of the decedent during the one(1) year period provided for under Paragraph 2, Article 17-1 of the Act is the estate, the valuation shall be based on the value of the estate on which the tax is levied; in case that payment is made with properties other than estate, the valuation shall be based on the value of such properties on the payment day, the related provisions of the valuation of the estate shall apply mutatis mutandis.