>Ok, let me talk this through. Each trip is an invoice. Along with the trip information, I have a field for how much is paid on that trip. When a check comes in, I go trip by trip, paying them off until I run out of money. It's a little more complicated for me because I have to apply it to trips that are a certain amount old rather than the oldest, but I think I can handle that part. Is that right?
>
>So what do I do if I run out of trips before I run out of money to apply? Where do I put the credits?
>
>I'm still confused on how I make the statements from that. If I'm not storing the balance anywhere, how do I calculate the balances?
>
>I appreciate you taking the time to help me through this. Hopefully I'll "get it" soon. :)
>
Michelle,

You get the balance by adding up the unpaid amounts for the invoices. I sure hope I don't get a bill and make a payment and not see it wipe out my oldest balance. You have two choices of accounting approaches here, open balance which you said you want, and open item which requires that each invoice have payments applied to it manually, meaning someone has to distribute the payment to specific invoices.

As for tracking overages, you can add a new invoice with a CM in front of its ID and give it a negative balance equal to the amount left over. That is called a Credit Memo and it is the standard accounting way of handling over payments.