Household Registration Act Article 3

The household registration shall be made on a household basis.All members living together in a family or a place under the same household head, or engaging in a joint business shall belong to one household, with the head of the household or the managing person as the head of the household. One who lives independently shall constitute a household with himself/herself as the head of the household. One person cannot be registered in two households.
中文原文 戶籍法第3條
戶籍登記,以戶為單位。
在一家,或同一處所同一主管人之下共同生活,或經營共同事業者為一戶,以家長或主管人為戶長;單獨生活者,得為一戶並為戶長。
一人同時不得有二戶籍。

English translation for reference only; the Chinese text prevails. Not legal advice.