Enforcement Rules of the Trademark Act Article 20

The period of six months as prescribed in Paragraph 1 of Article 20 of the Act shall be counted from the day following the date of filing of the first application in a country which has reciprocal recognition of priority rights with the Republic of China (ROC) or with a member of the WTO to the filing date as prescribed in Paragraph 2 of Article 19 of the Act.
中文原文 商標法施行細則第20條
本法第二十條第一項所定之六個月,自在與中華民國相互承認優先權之國家或世界貿易組織會員第一次申請日之次日起算至本法第十九條第二項規定之申請日止。

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