Is Zakat obligatory on inherited money that does not reach the minimum threshold after deducting expensive and ongoing marriage and medical expenses?

If the inherited money from parents reaches the nisab (the minimum amount on which zakat is due), then zakat becomes obligatory on it. Zakat does not decrease wealth; rather, it increases and develops it, as the Prophet (peace be upon him) said: "Wealth is not decreased by sadaqah (charity)." Furthermore, Allah will replace for the giver many times what he has spent, as Allah Almighty says: "And whatever thing you spend [in His cause] - He will compensate it; and He is the best of providers." (Qur'an 34:39)

Among the causes of healing from illness is the giving of zakat and increasing sadaqat (charities), as in the hadith: "Cure your sick with sadaqah."

As for the prospective wife's dowry (mahr), it is not an obligatory debt at this moment. However, upon the marriage contract, half of it becomes an established debt, and upon consummation, the entire dowry becomes established. At that point, the debt is deducted from the wealth, and the remainder is subject to zakat if it reaches the nisab.