Saving Customer Unused Credit in Access Desktop Services

[kashrus]

I am using Access Desktop Services as a billing program. Is there a way to save an overpayment anywhere so that when I enter a new invoice for the customer I will see that they have a credit?

[ranman256]

You'll have a form for the customer (single record )
when you open the form on this customer,you'll have 2 sub forms,
1 to show credits ,
1 to enter debits.