Does zakat apply to a sum of money given to a son to help him purchase a house, which was considered a debt to be deducted from his share of the inheritance after death?

Scholars differ concerning the ruling on zakat (definition) for debts. The preponderant opinion is that if the debtor is solvent and not procrastinating, then the owner of the debt must pay zakat on it, as it is like a trust. However, if the debtor is insolvent or procrastinating, then there is no zakat on it until its owner receives it. Once he receives it, he pays zakat on it for one year. Accordingly, if your son is solvent, you are obligated to pay zakat on the mentioned amount if it reaches the nisab (definition), either by itself or when combined with your other possessions.