Allocating receipts

When payments are received they need to be allocated to one of the following so that an accurate statement for the customer can be drawn up.

• Opening balance.
• Invoices, either paid in part or in full.
• Credit notes, either paid in part or in full.

If it's not clear which invoices are being paid off (maybe a remittance advice wasn't supplied) the general rule is to pay older invoices first.