Ability to make time not billable

Need to allow for time to be marked as not billable. Example: I want to have my team run the time clock so I know how much time they spent on a client but not billing the client for the hours. This is helpful for to keep time of a project that has a flat fee or time spent on a client when a mistake was made by my team. Im not going to charge the client for my teams mistake but need to still have my team clock in on a project.