nondeductible terminable interest rule

non·de·duc·ti·ble terminable interest rule /ˌnän-di-'dək-tə-bəl-/ n: a rule in estate tax law: the value of a property interest that passes to a surviving spouse may not be deducted if it passes from the surviving spouse to another person for less than adequate consideration upon the happening of some event (as the passing of a period of time)