The idea of sending a deal memo was given to me by a very experienced freelance producer that I have worked with at several studios. Their advice has always been useful to me over the years, and this time it was no exception. The purpose of the deal memo is to just make sure that both parties understand the agreement fully before going into a booking. In some cases, it can be used to protect yourself legally, which is why you need to choose your words properly.
Example:
