What is the ruling on zakat if the money reaches the nisab and a year passes, then it increases or decreases?

Zakat becomes obligatory on wealth if it reaches the nisab (threshold) and a full hawl (lunar year) passes over it. Wealth exceeding the principal capital is divided into two types: The first is that which results from the principal capital, such as profit. This is added to the principal and zakat is paid on it along with it, and its hawl follows that of its origin. The second is that which does not result from it but is of the same kind. In this case, the owner has the choice between adding it to the principal capital and paying zakat on it along with it when the hawl of the first wealth is completed, or initiating a new hawl for it and paying zakat on it upon its completion, even if it is below the nisab on its own. If the wealth at the end of the year is less than the nisab, then there is no zakat on it.