What should one do who invested his money in real estate and could not ascertain his profit from his loss until after two years, and how does he pay zakat on his money for the years following the investment when he does not possess liquid funds for zakat?

Zakat (definition) is obligatory on invested capital—both its principal and profits—every year if it reaches the nisab (definition) and a full lunar year (hawl) has passed over it. It is not permissible to delay its disbursement without a valid excuse. Zakat must be disbursed at the end of the first hawl if the amount of profit or loss can be ascertained; otherwise, zakat becomes obligatory at the end of the second year. The zakat payer must endeavor to estimate the amount at the end of the first and second hawl and disburse one-quarter of one-tenth (2.5%) for each hawl that the nisab was met, in order to clear their liability. Zakat must be disbursed for all past years if its disbursement was delayed. One should act upon their best judgment in estimating the wealth and years if in doubt. For zakat to be obligatory on profits, they must arise from lawful, permissible transactions. As for unlawful wealth, zakat is not obligatory on it; rather, it must be disposed of by spending it on charitable causes. It is not permissible to deposit money in interest-based banks except in cases of extreme necessity, and investment is not considered a necessity.