If a trust that took effect before the effective date of the Trust Act (including, for a trust created by will, one for which the will was made before the effective date of the Trust Act, and excluding a trust prescribed in the proviso to Article 13, paragraph (1) of the former Income Tax Act; hereinafter referred to as an "old trust" in this Article) comes to fall under a Trust Subject to Corporate Taxation (excluding a trust set forth in Article 2, item (xxix)-2, (b) of the Corporation Tax Act) on or after the effective date of the Trust Act, the provisions of Article 6-3, item (vi) of the new Income Tax Act apply by deeming that old trust to be a trust whose beneficiary, etc. prescribed in that item is deemed to hold the assets and liabilities belonging to its trust property.