It used to be that children of foreign fathers were allowed legal residence on account of their mother's ROC citizenship only until age 20, after which time their visas would switch to tourist status unless they held a student ID or a working visa for overseas Chinese. As tourists, they had to leave Taiwan once every six months.
過去法令規定，外籍孩子依法可以「依母居留」到二十歲，但滿二十歲後，若沒有在學或外僑工作證，身分立即成為「觀光客」，必須每半年出國一次。