Mark time entries (and bookings) as billable or non-billable
A check box in both a booking and time entries to mark them as billable or non-billable. In the case of the booking, the resoure will know if it is billable or not. In the case of time entries, one can run a report (say weekly) to find all billable time and accounts can issue invoices accordingly.
We are looking at the time entry side for this. Within the booking side you can do this easily by setting a custom booking rate of $0 for example, making it non billable work.
We are looking into this, so more updates to come to make it easier for you to handle and differentiate.
I'm a bit shocked this isn't already in the product. As someone else mentioned in the comments, this is really critical functionality for any time tracking product.
This is a pretty critical feature for the time entry side. Sometimes there are situations that you still want to know work has been done on a certain project but you just can't charge it to the client.