A takkanah (Hebrew: תקנה, romanized: taqqānā, plural takkanot) translated as 'improvement', is a major legislative enactment within halakha, the normative system of Judaism's laws. A takkanah is an enactment which revises an ordinance that no longer satisfies the requirements of the times or circumstances, or which, being deduced from a biblical passage, may be regarded as new. A takkanah is enacted by rabbinical decree or ordinance, issued to improve and preserve religious life. It is, therefore, the antithesis of the gezerah (Hebrew: גְּזֵרָה, romanized: gǝzērā). The term is applied also to the institution provided for in the enactment.
Takkanot were enacted even in the time of the Second Temple, those of unknown origin being ascribed to earlier leaders, and they have been promulgated at all subsequent periods of Jewish history.