If the Mahr of a woman reaches the Nisab and a full Hawl passes from the contract of marriage

Q 2: The deferred Mahr (mandatory gift to a bride from her groom) of my wife has been due on me for about ten years. She asks if Zakah is due on this deferred Mahr? If it is due, how should it be calculated? It should be noted that I cannot repay this deferred Mahr on demand and it forms a Nisab (the minimum amount on which Zakah is due).

A 2: The Zakah is due on the Mahr if it reaches the Nisab and a full Hawl (one lunar year calculated from the time a property reaches the minimum amount upon which Zakah is due) passes from the contract of marriage because the wife owns it upon concluding the contract of marriage. Thus, it is Wajib (obligatory) on your wife to pay the Zakah due on her Mahr during the past period.May Allah grant us success. May peace and blessings be upon our Prophet Muhammad, his family, and Companions.