Peace be upon you.

I bought a house in installments via an ordinary bank and I am still paying the monthly installments. However, I saved a sum of money for travelling that reached the nisab (basic minimum). Do I have to pay its due zakat? I also received money for a debt from one of my relatives which reached the basic minimum; it remained with him for more than three years. How do I calculate its due zakat? May Allah reward you.

Peace, Mercy and Blessings of Allah be upon you.

Praise be to Allah; Prayers and Peace of Allah be upon the Messenger, his household, his companions and those who followed his guidance.

Long term debts are not subtracted from the existing zakat money; rather, what is subtracted is the current installment for the year for which the zakat is paid. You pay the zakat on the rest of the money. Concerning the debt you retrieved after a period of three years, if the settlement of that debt was expected, in other words the debtor was rich and admitting the debt, then you must pay its due zakat  for each year. If the settlement of the debt was not expected, as in the case of an insolvent debtor or denying the debt, you do not have to pay its zakat until you receive it. After you receive it, you pay zakat for one year even if it had remained with the debtor for many years. And Allah knows best.