If it is just a few then use the money when it finally comes in, in January when it is needed. I have a few that do this and I don't really mind it. You can "state" all you want in a contract but, if they want to use their money for something else then it's not going to matter what was "stated" in the contract. My question is -Do you really have the time and money to do all of this with a contract? I don't. Many years in business without contracts and don't use them unless a business wants one.