Zakah is obligatory on the income from houses and buildings prepared for rent

Q: Is zakah obligatory on houses prepared for rent? And when does zakah become obligatory?

A: There is no zakah on houses prepared for rent, because there is no indication of that in the Shari'ah. However, if they are prepared for sale, then there is zakah on them, just as there is zakah on land prepared for sale and other trade goods.
Zakah is not obligatory more than once in the year. So whenever a full lunar year passes over zakatable wealth, whether money, land, or other trade goods, zakah becomes obligatory. If the wealth is spent before the completion of the lunar year, then there is no zakah on it. The same applies to the rent from houses prepared for rent: if the lunar year passes over it before he spends it, then zakah becomes obligatory on it if it reaches the nisab or more.
The nisab is one hundred and forty mithqals of silver, and twenty mithqals of gold. Its equivalent in today's currency is eleven pounds and three-sevenths of a pound of gold. As for silver, its equivalent is fifty-six riyals, or the paper money that serves as its substitute. If the wealth is less than that, then there is nothing in it. May Allah grant success.