Is zakat obligatory on an amount of 14,0 Jordanian Dinars lent to a brother, given that the latter is repaying it in monthly installments, and with current house installments and household obligations?

Zakat is obligatory on the amount loaned to your brother if it reaches the nisab on its own or when combined with other money or trade goods. Household expenses do not exempt one from Zakat. Regarding debts owed by the one paying Zakat: if he possesses other funds exceeding his needs that can cover his debts, then he must pay Zakat on the full amount. However, if he does not possess such funds, he should deduct his debts and pay Zakat on the remainder if it reaches the nisab.