ANSWER:
This is not how zakat is calculated. Zakat is owed over any cash and gold savings that you have been with you for over a lunar year and reaches the nisab. You do not subtract household expenses and pays of servants from it.
Zakat on loan:
If you ask them for the money every year and insist on getting it back and they apologize that they don’t have or refuse to give it back, there is no zakat on it until you receive it!
But if you are shy to ask, then you must pay zakat every single year.
Zakat on a property:
Zakat on a property is only if it is being displayed for sale.
https://youtu.be/bg62qw25tIc