To examine which payments have been completed in full and which have an outstanding balance or have not been paid:
Select Reports from the Reservations menu
Use the "Reservations" report
Select a Date Range and click on the "Due" column on the far right to view any outstanding balances.
You can also sort by Source, Booked Date, Check-In Date, or Check-Out Date by clicking on the Reservations tab at the top of Reporting Center and making a selection.