While rare, overpayment is a possibility of rentals. Sometimes checks come in for more than they should, or items are funded multiple times by mistake (ie., a deposit is received in cash for more than it should have been, then the original balance is paid by check). We need to be able to take "overpayments" on invoices, which can be converted to credit or as refund. Right now I cannot apply an overpaid check to an invoice.