How can you pay Zakat on borrowed money?
Zakat is paid by a Sahib e Nisab under Islamic principles @ 2.50% per annum on his savings in monetary terms, gold and silver, and tradeable goods according to the set principles of Islam. Zakat is referred to as arms to the poor and needy or charity. Generally, it is a small percentage, but all say, the example of those who spend in the good cause of Allah is like the example of the seed.
The question always arises in everyone’s mind is whether Zakat applies to the money they have loaned or borrowed money. No, As far as money is lent or borrowed or anything lent, whether gold is given on loan or silver, cash or currency, the person who owns that has to pay Zakat on it. The person who owns that borrowed money has to pay it, but the person who uses it does not have to pay Zakat.
Zakat is Obligated to what people?

Zakat is to take the wealth from the rich people and pass it along to those that happen to be in need. Zakat is obligatory upon the individual who fulfills five conditions:
1. You must be a Muslim
2. A person who is free and has a right to his wealth
3. You must be mature
4. Sanity
5. One must have Nisab
When the individual gives Zakat, the recipient does not need to know Zakat. However, it is an obligation on the giver to ensure that the recipient can receive Zakat.
Zakat On Borrowed money
If you borrowed money, most likely if you borrow money you feel you do not possess it anymore but let’s assume that you borrowed 10,000 Euros from a cousin and you have that money in your bank account for a whole year so if you did not give it back then you have to pay Zakat on it.
You are obliged to give 2.5% Zakat on it. When Prophet dispatched his men to collect the Zakat from all over the tribes, the zakat collectors would see a herd of sheep and tell them that they have to give ten sheep as a Zakat. The zakat collectors do not ask and inquire about this all yours or borrow some of it, which means they take Zakat whatever is in your possession.
Business deal:

If the money is given to someone as a business deal saying that we share the profit, it is your money, yet you have to pay the Zakat on that money.
Secured loan:
If you give a loan to any relative or friend without any bribe for the sake of Allah, it will be a secured loan if the person is rich and return it to you, on that you have to pay Zakat every year. You have to pay every year the Zakat on that amount.
Unsecured loan:
The other type of loan is an unsecured loan; for example, the person you have given to us may be inadequate, and you have doubts that he will be able to repay the money or not. If you don’t want to pay for an unsecured loan, you need not spend every year. If you do not get the cashback, you do not have to pay Zakat on it, But if you get it, then maybe after five years, you have to pay for all the years you had lent.
Conclusion:
In a nutshell, if you borrowed money, you have to give Zakat as long as the full lunar year had passed and it reached a threshold, so you have to give it.
Also read: zakathttps://en.wikipedia.org/wiki/Zakat