The Ruling on the Zakah of the Value of Cars Sold on Installment

Question:
I am a man who sells cars on monthly installments. Some of them I receive the value of within one or two years, and some take longer than that. The question is: what is the zakah on this amount? Is it on the entire amount, or only on what I receive within a year? And if I am receiving post-dated checks, what is the ruling on that? And if I put something into a charitable project, such as a Qur'an memorization school or something else, is that valid?

Answer:
For everything that completes a lunar year, you are obligated to pay zakah on the wealth you have, whether it is in your possession or in the debts owed to you by people—loans, car prices, or otherwise. The debts you have against people, if the year has completed, you pay zakah on them along with the money in your hand. You total up what you own and pay zakah on it by giving one-fifth of a tenth. Even if it is on installment or otherwise, because it is your lawful right and your property, and a year has passed over it, zakah is obligatory on it. Yes.