(1)Subject as hereinafter provided, the income of the estate of a deceased person shall be chargeable to tax in the hands of the executor,-(a)if there is only one executor, then, as if the executor were an individual; or(b)if there are more executors than one, then, as if the executors were an association of persons;and for the purposes of this Act, the executor shall be deemed to be resident or non-resident according as the deceased person was a resident or non-resident during the previous year in which his death took place.