What is the ruling on depositing money in variable-return investment certificates at the National Bank of Egypt, while receiving annual profits and paying zakat on the entire sum, including the profits?

A Muslim must pay zakat on his capital if it reaches the nisab and a full year has passed over it. He should also pay zakat on his profits along with the principal if they are permissible (halal). As for profits gained from illicit sources, such as usurious interest, there is no zakat on them due to incomplete ownership. Instead, one must dispose of them by spending them on charitable and benevolent causes. Furthermore, money should be withdrawn from usurious banks. Allah Almighty says: "And if you repent, you may have your principal – [thus] you do no wrong, nor are you wronged." (Al-Baqarah: 279)