Enforcement Law for Part IV, Family Law of the Civil Code Article 5

The period specified in Article 987 of the CIVIL CODE during which a woman shall not remarry shall be reckoned from the date of the dissolution of her [former] marriage relationship as well, although the marriage relationship was dissolved before the coming into force of the PART of FAMILY of the CIVIL CODE.
中文原文 民法親屬編施行法第5條
民法第九百八十七條所規定之再婚期間,雖其婚姻關係在民法親屬編施行前消滅者,亦自婚姻關係消滅時起算。

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