You can run an Uninvoiced Charges report from the "Who Owes You" section in the Reports tab. When the report loads, select Customers in the Group By field. Then you can run down the list and look for the Customer that you are trying to make inactive. By clicking on the Billable Charge that was assigned to that Customer, you can click on Expense (blue hyperlink at top of page) un-select the Billable option once the Expense opens, Save and Close, if you do not intend to Invoice that Customer. If you DO plan to charge the customer, you'll need to create a new Invoice for them, and Add the Billable Expense that will pop open from the right hand side of the Invoice, Save and Send. If there are too many Uninvoiced charges to do this, I recommend contacting your bookkeeper or accountant because we have the ability to "batch clear" those types of older transactions. Hope this helps!