Is it permissible to pay deferred dower from Zakat funds?

A husband is not permitted to pay his zakat to his wife as a deferred dower (mu’akhar sadaq); this is because the dower is a debt owed to her. However, if the intention is to pay zakat to a husband who is indebted to his wife, then this is permissible if the husband is in debt and unable to repay it, whereas it is not permissible to pay him if he is capable of fulfilling his debt.