Is Zakat obligatory on a sum of 3,500 US dollars saved in a bank, what is its amount, and is the husband's money added to it when calculating it?

Zakat is obligatory on saved wealth if it reaches the nisab (minimum threshold) and a full lunar year (hawl) has passed, unless there is a debt that reduces the wealth below the nisab after deducting it, and there is no other non-zakat-able wealth to cover the debt. The amount of zakat is one-quarter of one-tenth (2.5%) of the net wealth after deducting the debt. The husband's wealth is not added to the wife's wealth when calculating zakat.