Is zakat obligatory on an investment certificate that reaches the nisab and whose returns are spent on living expenses, knowing that it may be usurious?

The ruling on the returns from savings certificates in banks depends on the nature of the transaction:

1. In Islamic Banks: If the certificates are based on legitimate Mudarabah (definition) (profit-sharing) in accordance with Sharia (definition) principles, then they are permissible, and their profits are lawful. Zakat (definition) is obligatory on both the principal capital and the profits upon the completion of a full lunar year, at the rate of one-quarter of one-tenth (2.5%). 2. In Usurious Banks: Certificates are considered a loan, and their returns are Riba (interest/usury). One must dispose of these returns by giving them to the poor and needy. They cannot be counted as part of one's Zakat, nor is it permissible to benefit from them unless one is poor and in need. One must withdraw money from these certificates and cease dealing with them.