Is Zakat obligatory upon a person who apostatizes before a full Hijri year passes over their wealth?
Chapter on Zakat on Debt and Charity
Al-Mughni
Book of Zakat
Primary text
Zakat is not obligatory upon the apostate if the apostasy occurs before the completion of a full lunar year over their wealth, even if they remain in apostasy until the year ends. This is because Islam is a prerequisite for the obligation of Zakat, and its absence during a portion of the year invalidates the Zakat obligation, similar to the prerequisite of owning wealth or reaching the Nisab threshold. If the apostate returns to Islam before the year completes, they must restart the calculation of the Hawl (full year) from the time of their return.
Supporting text
Imam Ahmad holds that if an apostate embraces Islam after the Hawl has already passed over their wealth while they were an apostate, they do not pay Zakat on it immediately but must complete a new Hawl because they were previously prevented from fulfilling the obligation. If apostasy occurs after the Zakat liability has been established (after the Hawl), Zakat is not waived.