You can raise various kinds of invoices aside from final invoices (read here to see which other invoice types you can use). An additional or interim invoice will create an invoice, but not mark the job as closed. A final invoice will close the job off.
- First, search for the invoice you'd like to convert, click the invoice number in the search results.
- Click 'View' next to the invoice.
- Click 'Edit' on the invoice (Invoice breakdown section).
- At the top of the page, you will see a dropdown for invoice type.
- Click 'Final invoice' and then 'Save' at the bottom of the page.