Must money held in another bank account and credit card funds, such as Visa, be included in the money subject to Zakat?

If you have saved the equivalent of the nisab — which is 85 grams of gold or 595 grams of silver — and a full lunar year (hawl) has passed on it, then zakat is obligatory upon you. It is not a condition that the money be in a single account. As for a covered credit card, its balance is owned by you and should be added to your wealth when calculating zakat if a full year has passed on it. However, an uncovered credit card does not have a balance owned by its holder.