What is the ruling on zakat for a livestock farm (cattle and buffalo) that is shared with a farmer who takes one-third of the profit and milk in exchange for his work, and is zakat due on it annually or only upon sale, and what is the ruling concerning past years if zakat was not paid on it?

If the aforementioned transaction is in the form of Mudarabah (profit-sharing), it is not valid because the capital must be in cash. Similarly, it is not valid as an Ijarah (leasing/hiring) because the wage is unknown. However, if the Ijarah was concluded for a known period with one-third of the livestock now, or a known portion thereof, it would be valid.

If the transaction is invalid, the worker is entitled to a fair wage (ujrat al-mithl), and the offspring and profits belong to the owner of the livestock.

As for zakat, it is obligatory on these animals as zakat on trade goods if they reach the [zakat] threshold (nisab) and a full year (hawl) passes over them. The livestock should be valued annually, and one-quarter of one-tenth (2.5%) of their value should be given out. It is obligatory to hasten in paying the zakat for all past years if it has not been paid. If it is difficult to ascertain the exact calculation, then one should make an earnest effort (taharri) until one is reasonably certain that one has fulfilled their obligation.