Is Zakah due from both the principal and the profits?

Q: A man who has a sum of money that has already reached the Nisab (the minimum amount on which Zakah is due) pays the due Zakah (obligatory charity) thereon. However, before the end of the next Hawl (one lunar year calculated from the time a property reaches the minimum amount upon which Zakah is due), the sum increased and then I invested this increase with a partner setting out a project for printing one of the Islamic books. The next Hawl came to its end while this sum was still with my partner. How should I pay the due Zakah on this part of the money? Should I pay the Zakah on the original capital given to the partner or should I wait until the completion of the project to identify the profit/loss and then determine the due Zakah? It should be noted that my partner does not have the whole capital of the project; he rather takes the necessary requirements and substances for the project by paying a portion of the payable sum and the remaining part is to be paid later after a certain period of time, during which the book is expected to be distributed. The same kind of treatment is also adopted with regard to the printing press, binding, and similar affairs. In other words, the project costs a certain sum of money but starts with only a portion of the sum and the remaining portion is a debt due to the relevant parties. A: You should pay the Zakah due on the original capital and the profit thereof whenever the Hawl is complete (Part No. 8; Page No. 72

A: You should pay the Zakah due on the original capital and the profit thereof whenever the Hawl is complete (Part No. 8; Page No. 72) and it should be evident that the Hawl of the profits is the same Hawl specified for the original capital.May Allah grant us success. May peace and blessings be upon our Prophet Muhammad, his family, and Companions.