Tax Collection Act Article 48-3

A taxpayer who has violated any provision of this Act or any other applicable tax law shall be dealt with according to the law in force as of the date on which the punishment for such violating act is imposed; however, if the relevant provisions of the law applicable prior to the imposition of the punishment for such violating act are more favorable to said taxpayer, such favorable provisions of the law shall prevail.
中文原文 稅捐稽徵法第48-3條
納稅義務人違反本法或稅法之規定,適用裁處時之法律。
但裁處前之法律有利於納稅義務人者,適用最有利於納稅義務人之法律。

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