Is Zakat obligatory on past and future payments made for investment in a hospital construction project that has not yet been completed?

Money paid for building a hospital is not subject to Zakat. Zakat is only obligatory on its profits if they reach the nisab (minimum threshold) and a hawl (full lunar year) has passed over them. As for money designated to complete the construction, Zakat (2.5%) is obligatory on it if a hawl has passed over it while it is in your possession and it reaches the nisab along with your other wealth.