Regulations Governing the Declaration, Inspection, Duty, and Release of Personal Luggage or Goods of Inward Passengers Article 17

Where the personal luggage or goods of inward passengers exceeds the limits set in Article 4, Article 14, Article 15, or Article 16, the passenger is obliged to submit an importation permit or documents issued by the relevant competent authority for examination, or process the return of such excess portion, or declare the abandonment in writing within 2 months from the day following passenger's date of entry. The two-month period may, upon application, be extended for one more month when necessary. Where the passenger fails to do so before the deadline, the provisions of Article 96 of the Customs Act shall be applied.
中文原文 入境旅客攜帶行李物品報驗稅放辦法第17條
入境旅客攜帶進口之行李物品超過第四條、第十四條、第十五條或第十六條規定之限制範圍者,應自入境之翌日起二個月內繳驗輸入許可證或相關主管機關核發之許可或證明文件,或將超逾限制範圍部分辦理退運,或以書面聲明放棄;必要時得申請延長一個月;屆期未辦理者,依關稅法第九十六條規定處理。

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