Is it necessary to verbally authorize the husband to pay Zakat, and is anything required for not having authorized him previously?

A wife is not required to authorize her husband to pay zakat on her behalf; rather, delegating someone to pay zakat is permissible. The Prophet (peace be upon him) appointed collectors to receive zakat and entrusted Ali with the sacrifice of the pilgrimage animals, demonstrating the validity of delegation. However, a husband cannot pay his wife's zakat without her knowledge and consent, as the intention of the zakat payer is a necessary condition. Additionally, no specific wording is required when delegating someone; any expression that conveys the intended meaning is sufficient.