You could raise a zero-value order on the client, using any layout eg service, and then apply the advance payment to the order. A credit wil be created which you can then settle against time billing invoices in the future.
If you are in a GST regime, you may need to take care to account for the GST correctly.
Rgards Mike
Posts: 40 | Location: New Zealand | Registered: Mon February 09 2009