Alms Tax: Becoming Baligh, Sane, or Rich Before Sunset
Practical Laws of Islam as per the teachings of Ayatullah Sistani
Ruling 2010
If before sunset a child becomes bāligh, or an insane person becomes sane, or a poor person becomes rich, and if that person meets the conditions that make it obligatory for one to give fiṭrah, he must give fiṭrah.
-Ayatullah Sistani, Practical Laws of Islam, Alms Tax (Zakat)