How much money can be taken, and how much must be given as charity? Can the annual fees of the institution be accounted for from investment returns? Is zakat obligatory on this money now, or after a year if it is not spent?

If the amount of haram money from investment returns is unknown, one must strive to estimate the proportion of the haram and donate it to the poor and needy. Taxes or fees are not to be considered part of this proportion. Zakat is obligatory on the remaining (halal) amount once it is received, by giving out one-quarter of one-tenth (2.5%) a single time.