Is a working wife who spends her salary on her husband's household obligated to pay zakat and give sadaqah from her own money, or does she rely on her husband to pay zakat on her behalf?

If the salary reaches the nisab (the minimum amount on which zakat is due) by itself, or by combining with money or trade goods, and a full lunar year (hawl) passes over it, then zakat becomes obligatory on it. The person responsible for paying it is the owner who is not legally incompetent. However, if the salary is spent on expenses, or if what remains of it is less than the nisab, or if a nisab remains but a full year has not passed over it, then zakat is not obligatory on it.