About project invoicing

To invoice customers for the services provided as a part of a project, you can generate invoices based on the information collected in the Projects module.
The invoicing procedure is available only for external projects or for projects associated with customers.
You can run the invoicing procedure automatically, manually, or on a schedule.

You can enable draft invoices for a particular project, which gives you the ability to review and modify invoiceable transactions and amounts in a draft invoice before you prepare the final sales invoice with all information copied from the draft invoice.