How is the zakat calculated for a project of building an apartment building and selling its units upon completion of construction, and when is its due date? Is each partner responsible only for the zakat of his share, and is one who refrains from paying his share sinful?

Real estate prepared for sale is considered trade goods. Zakat (definition) is due on it by valuing it at the completion of a hawl (lunar year) on the original capital designated for its construction, or on the money that reached the nisab (definition) (minimum threshold) and was invested in its construction. Each partner should assess their share; if it reaches the nisab on its own or when combined with other money, they must pay one-quarter of one-tenth (2.5%). If it does not reach the nisab, then no zakat is due on it until it does. Partnership does not affect the zakat on trade goods; their ruling is the same as that of individuals. Zakat is obligatory annually and should not be delayed until sale, as long as the partners are capable. However, if the partners are not capable, it is permissible to postpone the payment of zakat until funds become available or the property is sold. Then, they must pay zakat for all previous years based on the property's value in each respective year. Whoever refrains from paying zakat while knowing its obligation is sinful.