Reoccurring Invoices are most commonly used when an engagement has been accepted that requires the client to pay a set amount per specified time frame. Best practices here would be to make sure that you are allowing the reoccurring invoice to automatically relieve specific sets of billable time. It is very beneficial, especially for flat rate engagements, to continue to track billable time for those jobs. It allows for you to see not only whether that flat rate covered the amount of billable time tracked but also to make sure that your staff is continuing to be efficient in their flat rate work. Even as the industry embraces the concept of Value Billing, you still need the billable time to back up that value.