The first step is to classify the “lowest annual rental receipts” of mercantile occupancies on the ground floor on both sides of business road into three categories. The “lowest annual rental receipts” of the mercantile occupancies on the second floor or above is defined as the 30% of that of the ground floor. The second step is to classify the “lowest annual rental receipts” of mercantile occupancies on the ground floor on both sides of non-business road into four categories according to the area sectors. In this area, the “lowest annual rental receipts” of the mercantile occupancies on the second floor or above is defined as the 30% of that of the ground floor. The third step is to classify the “lowest annual rental receipts” of offices building and office accommodations into four categories according to the area sectors. The fourth step is to classify the “lowest annual rental receipts” of the industrial occupancies into two categories of the standard premises according to the architectural structure. The fifth step is to classify the “lowest annual rental receipts” of other occupancies into four categories according to the area sectors. Since this method was enforced, the annual taxation amplitude of rental industry is over 30%.