Patent Act Article 54

Deemed to have been extendedWhere a request for patent term extension is filed in accordance with the preceding article, the patent term shall be deemed to have been extended if the Specific Patent Agency has yet to render a decision before the original patent term expires. However, where such request for patent term extension is not allowed, the patent term shall expire on the original expiration date.
中文原文 專利法第54條
依前條規定申請延長專利權期間者,如專利專責機關於原專利權期間屆滿時尚未審定者,其專利權期間視為已延長。
但經審定不予延長者,至原專利權期間屆滿日止。

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