How is the Zakat calculated for an amount of EGP 10,000 deposited in investment certificates at the National Bank of Egypt, which yields a return of EGP 575 every six months?

Zakat is due only on the value of the investment certificates, which is 10,000 pounds. These certificates must be disposed of, and one should not deal with interest-based banks except out of extreme necessity, such as keeping money in a current account when there is fear of its loss. What has been spent from previous profits does not need to be replaced; rather, only what remains of it must be given out.