Is Zakat due on the principal amount of money invested in my deceased brother's factory, or only on the profits generated from it after deducting living expenses?

If the agreed-upon percentage for mudarabah (profit-sharing) at the time of contract ranges between 10-15%, then the transaction is invalid (fasidah) and must be annulled. In such a case, the profit and loss belong to the capital owner (rabb al-mal), and the worker (amil) is entitled to a fair wage (ujrat al-mithl). However, if the agreement is for a specific, predetermined amount, then the transaction is valid. The worker's debt does not negate the zakat on the mudarabah capital, nor does it negate the capital owner's share of the profit. Zakat is obligatory on both the capital and the profits together, except for what was consumed before the completion of the hawl (one lunar year). Zakat is not waived due to the accumulation of years. Fixed assets not intended for trade are not subject to zakat.