The effective date when a law, contract, or agreement comes into force.
この契約の発効日は署名日とする。
The effective date of this contract shall be the date of signature.
新しい規則の発効日は来月の一日だ。
The effective date of the new regulation is the first of next month.
保険の発効日は手続き完了の日からとなる。
The insurance becomes effective from the day the procedures are completed.