Invoice payments represent payments made by customers of a business.
Payments may be made at any time and applied to any outstanding (sent, but not fully paid) invoice.
Whether or not the fee is passed to the customer. It is paid by the business otherwise.
When calculating the outstanding balance on the invoice, only the portion of each payment allocation that is applied to the invoice (excluding pass-through fees) is considered. This allows customers to pay the invoice amount plus any pass-through fees without the invoice being considered overpaid.
Invoice allocations allow specifying a payment to be for multiple invoices.
Most commonly the full payment will be allocated to a single invoice, but any number of allocations are allowed.
The sum of all allocations must be equal to the payment amount.