Is Zakat obligatory on the dowry (Mahr) and deferred dowry (Mu’akhar) if the husband does not possess sufficient funds to pay it, and the wife is not employed and has no income, especially since the dowry exceeds the Nisab?

First, there is no zakat on someone who does not own wealth. However, if you acquire wealth that reaches the nisab (minimum threshold) and a hawl (full lunar year) passes over it, zakat becomes obligatory on it, unless you spend it on furnishing the apartment or give it to your wife as mahr (dowry) before the hawl passes.

Second, the deferred sadaq (dowry) is a debt owed by the husband to the wife, and its zakat is like the zakat of other debts: 1. If the debt is owed by someone who is capable of paying and is willing to pay it, then its zakat is obligatory every year. 2. If the debt is owed by a poor person or someone who denies the debt, then according to the more preponderant opinion, there is no zakat on it. However, if the wife receives it, it is more cautious to pay zakat for one year. Based on this, the deferred mahr that will be used to purchase furniture has no zakat on you or on your wife, due to your lack of ownership of the wealth. As for the deferred dowry that the wife does not receive except after separation, there is no zakat on it for her unless she receives it, in which case it is more cautious for her to pay zakat for one year.

Sheikh Ibn Uthaymeen was asked about deferred sadaq and its zakat, and he answered that it is permissible, and that it is a debt owed by the husband that becomes due at a specific time or upon separation. Its zakat becomes obligatory on the woman if the husband is wealthy and willing to pay the debt, and she is not obligated to pay zakat if he is poor.