How is Zakat to be estimated if the wealth reaches the minimum threshold (nisab) in one month, then falls below it in the following month, then returns to reach the nisab in the month after that, and so on?

Zakat becomes obligatory on wealth if it reaches the nisab (minimum threshold) and a full lunar year (hawl) passes since it reached the nisab. If the wealth decreases below the nisab during the hawl, the hawl is interrupted. Then, if a person's ownership of the nisab becomes complete again, their hawl begins anew from the moment the nisab is completed for the second time.

Whoever wishes to follow the path of leniency may pay zakat on their wealth when a full year passes from the first nisab they possessed, whether the nisab remained present throughout the year or was interrupted.

In this case, the one paying zakat should look at whatever wealth they possess, whether little or much, and pay zakat on it. This is easier for them and more conducive to avoiding forgetfulness or negligence in paying zakat, and it also benefits the poor. However, there is no blame on someone who follows the first approach.