Enforcement Act of the Part of Obligations of the Civil Code Article 21
Obligations occurred before the coming into force of the Part of Obligations of the Civil Code may also be offset in accordance with the provisions of the Part of Obligations of the Civil Code.
中文原文 民法債編施行法第21條
民法債編施行前之債務，亦得依民法債編之規定為抵銷。