Is the zakat threshold determined by multiplying the price of one gram of 24-carat gold by 85? Is zakat due on funds that reach the threshold on the 4th of Rajab each year, even with monthly increases in the money? What is the zakat due date for gold purchased in Sha'ban?

The zakat threshold (nisab) for banknotes is the equivalent of 85 grams of gold or 595 grams of silver. The silver nisab is considered more beneficial for the poor. To calculate zakat on salary, you can assign a separate hawl (lunar year) for each salary payment, or, what is easier and more beneficial for the poor, is to pay zakat on all monetary savings when a hawl passes on the first nisab you acquired from them. As for gold not intended for adornment, its hawl is the hawl of the price at which it was purchased, as its purchase does not interrupt the hawl for zakat.