Am I obligated to pay Zakat after selling bonds I bought from an Islamic bank, given that I do not know when the bank pays its Zakat, nor whether it has paid it?

Firstly: There is no objection to Mudarabah (profit-sharing) and Ijarah (leasing) sukuk (Islamic bonds) issued by Islamic banks. Their concept is based on fractionalizing capital, whereby sukuk holders collectively contribute to forming capital for Mudarabah or for purchasing assets to lease. The issuance prospectus or the sukuk themselves must not contain anything that would sever the partnership in profit. It is not permissible to stipulate a fixed amount for sukuk holders. The subject of division is the legally permissible profit, not the revenue. Profit becomes due upon its appearance and is owned upon liquidation or valuation.

Secondly: The principal and profit of the capital in Mudarabah sukuk are subject to Zakat. As for the capital in Ijarah sukuk, Zakat is only on the rental income.

Thirdly: It is permissible for the bank to pay Zakat on the sukuk on behalf of their owners if this is stipulated in its articles of association or by a resolution of the general assembly, or if the law mandates it, or with authorization from the sukuk holder.

Fourthly: If the bonds are sold before the completion of a full year (hawl) and their proceeds are used for non-commercial needs, then there is no Zakat due on them. If the bank paid Zakat on them before the hawl, it is a non-obligatory charity. However, if the bonds are sold and commercial goods are purchased with their proceeds, the hawl is not interrupted, and Zakat becomes obligatory upon the completion of the hawl. What the bank paid is not counted unless it was intended as an advance payment of Zakat.