How do I see that a payment is from an On Account amount vs Unapplied amount?

I need to get a remaining balance for an aging report. I see payments in the AR_PAYMENT_SCHEDULES_ALL. That table also has a amount_on_account field. I can hardcode the logic:

case when aps.amount_on_account = 0 and (aps.amount_due_original*-1) <> aps.amount_due_remaining then 'Unapplied' when aps.amount_on_account <> 0 then 'On Account'

This is not ideal. When I look at the ar_receivable_applications_all table to get the status, the status of the row for payment is APP.

Here is a scenario:

A customer has 200,000.00 on account.

A 1,000.00 payment is made (the 1000 payment row in ar_receivable_applications_all has a status of APP, not ACC)