Alms Tax: Requirement for the Zakat Recipient to be a Twelver Shia
Practical Laws of Islam as per the teachings of Ayatullah Sistani
Ruling 1957
The receiver of zakat must be a Twelver (Ithnā ʿAsharī) Shia. If one gives zakat to a person he believes to be a Shia and later realises that he was not a Shia, then based on obligatory precaution, he must give zakat again even if he had made investigations about the person or he had relied upon something that was legally authoritative.
-Ayatullah Sistani, Practical Laws of Islam, Alms Tax (Zakat)