Report with list of bills linked to a client/customer

Hi, the reports mentioned here don't seem to give me the information I need.  We have clients who prepay for expenses.  In bills we pay we list them as the client so that it gets identified with them.  I am trying to find a report that shows all the expenses in a month that should be used to generate a journal entry report to debit the liability - unbilled account.  Every month I need to debit the unbilled spend account and credit the income account to show we have earned the $$ that we already received.  Thank you!