Section 17

Where estate duty has been paid under this Act or under any previous written law relating to estate duty in respect of any settled property, since the date of the settlement, upon the death of one of the parties to a marriage, no further estate duty shall be levied in respect of that property upon the death of the other party to the marriage, unless such other party was at the time of his death, or had been during the continuance of the settlement, competent to dispose of that property.