Expand the pledge schedule to include cumuative totals for Inistallment Payments and Actual Payments. Then add column to show arrears as an actual payment is made. Hard to explain but see attached spreadsheet.
Why? My Arrears Reports are always wrong - can't seem to handle donors who made unsceduled/irregular payments. The proposed format would show the arrears amount at a glance, instead of having to do eTap math in your head.