Ticket sales "must have zero balance to purchase" ignoring balances that have future due dates

In our ticket sales as well as general registration, we place the "must have zero balance to purchase" option in the back office. However, this is calculating future balances that haven't hit their due date yet. This is causing our desk a lot of extra work, a lot of our competition and costume fees are posted but the due dates aren't until later in the month or next month.