How is Zakat on money paid when the amount increases monthly? Is Zakat due on the original amount that has completed a Hawl (lunar year), or on the total amount? Is Zakat due on an apartment bought for a son and currently rented out? Is it permissible to pay Zakat to settle the debt of a younger brother who is unemployed?

If monthly acquired wealth is an increment to the principal (such as business profit), then it is subject to zakat along with the principal when its hawl (one lunar year) is completed. However, if it is not an increment to the principal (such as employees' salaries), then the majority of scholars hold that zakat is due on each installment when its hawl is completed. It is permissible to pay zakat in advance and combine it with the principal for ease.

There is no zakat on an apartment purchased for purposes other than trade. As for the rent of an apartment, its ruling is the same as that of acquired wealth.

It is permissible to give zakat to a brother if he falls under the categories of zakat recipients, such as being a gharim (indebted and unable to repay) or being poor/needy and unable to earn, provided that zakat is not given to the wealthy or to one who is strong and earning. Some scholars prohibit giving zakat to a single person under two descriptions simultaneously.