15%海外买家税适用于1-6个单位的民用住宅，不适用于：多单位租赁物业（超过6户），农业、商业、工业用地。

你看到的宣传的可能是不适用范围内的物业。

the nrst does not apply to other types of land such as land containing multi‑residential rental apartment buildings with more than six units, agricultural land, mercial land or industrial land