The Billing History tab displays closed invoices and their associated payments, write offs, refunds, etc.

Selecting the Actions button will allow members to apply payments on open invoices and download PDFs of the invoice, the payment, the refund, the write off, etc. 

An asterisk * in the Amount column indicates a voluntary fee that was not included in the original payment; these fees are optional and do not "count against" a member if they remain unpaid.