Customs Personnel Management Act Article 7

The probation term of newly recruited customs officers is 1 year in accordance with Subparagraph 1, 3, 4 and 5 of Paragraph 1 of Article 5 of this Act; anyone who is qualified upon the expiration of the probation term may take the post; anyone whose performance is outstanding, the probation term thereof shall be shortened to be six months. If the performance is not satisfactory, the probation term may be extended by civil service offices depending on the circumstances with a maximum of six months; however, further lack of qualification shall result in the discontinuation of probation term and the cancelation of position.
中文原文 關務人員人事條例第7條
依第五條第一項第一、第三、第四、第五款規定,初任人員須經試用一年,試用成績及格者,予以實授;其成績特優者,得縮短為六個月;不及格者,報請銓敘機關分別情節延長其期間,但以六個月為限;延長後仍不及格者,停止其試用,並予解職。

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