Is the amount of zakat paid on a bank balance correct, and how is zakat calculated after withdrawing 5,000 pounds for investment? Is it permissible to pay next year's zakat in advance to deliver it to Gaza, and when is the due date for paying zakat thereafter?

Zakat is obligatory on money if it reaches the nisab (minimum threshold) and a hawl (one lunar year) has passed on it. Its amount is a quarter of a tenth (2.5%), calculated by dividing the amount by 40. The value of dollars must be added to the total amount before calculation. As for medicines offered for sale, they are trade goods subject to zakat. Their value is calculated at the completion of the hawl and added to your existing money, and a quarter of a tenth is given from the total. It is permissible to pay zakat in advance, especially if there is a benefit in doing so, and paying in advance does not change the day of the hawl.