That would depend on your country’s legislation, on the project and the project owner.
Usually several conditions imply:
- The project owner is a non profit or a non governmental agency;
- The fund you give must be a proper donation, not a purchase;
- The project owner has to give you a receipt for your donation.
This must be managed by the project owner. For more details, check the legislation in your country and feel free to contact the project owner to see if it could apply to you.