How is the Zakat on money calculated for investment certificates with a quarterly return that have completed a full year (hawl), knowing that it is currently not possible to invest the money outside of banks?

If the profit results from usurious transactions, it is illicit wealth that must be disposed of by spending it on the welfare of Muslims, and it is not permissible to pay zakat on it. However, if it results from lawful transactions in an Islamic bank, then zakat is obligatory on both the profit and the principal capital every lunar year.