Client Level Billing is the practice of generating one physical invoice for all Matters of a Client.  The system actually creates a separate invoice for each Matter internally but all invoices are shown to the Client as one.   Accounts Receivable is tracked on a Matter basis.   Unless you are specifically required to do so by a Client, we strongly recommend you not use this feature.  Among other things, in order to use Client Level Billing, you must have set up special invoice styles. Also, if you need to unpost or void one Matter’s invoice, you must unpost all invoices created for that Client during that invoicing run.