(1)When any holding has been unoccupied and unproductive of rent for thirty or more consecutive days during any year and written notice of the fact has been given to the Chief Municipal Officer, he shall remit and, if the tax has been paid, shall adjust against future demands one-half of so much of tax of that year as may be proportionate to the number of days the said holding has remained so unoccupied from the date of delivery of such notice.
