Calculating zakaat

Q: Some years ago, there were some riots in a certain place. The valuables from the house were placed elsewhere. Some were taken to the business, which was a big wholesale, for safekeeping and placed in a remote part of the safe. Included in these valuables which were taken to the business was some jewellery which originally belonged to the mother who has since passed away. This jewellery has now been found after many years in which it was regarded as lost. There are two questions:

1. Is there Zakaat on this jewellery for the previous years?
2. The mother had left a note with the jewellery stating that it should be given to her youngest son who was 9 years old at the time. Is this gift valid?

Q: Someone let another borrow money. Is zakat to be payed on that amount of money that he let another borrow at the end of each year? or is it due after the money is returned to him?

Q: On what is the zakaat nisaab worked out on?

Q: My father died without giving the meher money to my mother. After my father's death my mother will get the meher money from his property. Then is it necessary to give zakat on that money calculated from the day of marriage or from the day my father died or the day my mother receives the money?

Q: In South Africa, Government taxes can amout to 40% of ones income. If any, how does this affect our annual zakaat?

Q: Please can you help with guidance on the following with regards to Zakaat:
My family have made an investment in a Shariah compliant business that pays out monthly returns.

Q: I want to pay my zakaat and I do not know the exact date. It was between February 18 and end of November when I was 9 years old. I am inclined towards more towards November that I became baligh. I do not know which date to choose. Which date must I choose?

Q: One is in the process of purchasing a property and pays the deposit to a bank & not the seller of the property. The bank then issues a guarantee (to the sum of the cash deposited) in favour of the seller of the property. The guarantees will be paid over to the seller once the property is transferred into the purchaser’s name.
At one’s Zakaat date the property has not yet been transferred and the cash is still at the bank in the form of a guarantee. Is such cash then Zakaatable?

Q: On the 1st of Ramadan I had £30,000, by the end of that year I had £15,000 - do I give zakat on £30,000 or on £15,000?

Q: I have given a loan to my cousin and he promised to pay me back in two months time. His financial condition is not good and he will pay late. Can I adjust it through my Zakaat money, by asking him not to pay back?