Within Teamwork Projects, you can add unbilled time logs to an invoice.
You can then mark the logged time as billed by marking the invoice as complete.
In the Billing area of your project, select the Unbilled Time tab.
Drag and drop
Hover over a time log to reveal the move icon to the left. You can then click and drag the time log over to the invoice on the left to add it to it.
To drag and drop multiple time logs together, select the checkboxes to the left of each time log. You can then use drag and drop to move all selected time logs at once.
Select an invoice
Once you have ticked time logs, you can use the Move Items button to select a specific invoice to move them to.
In the invoice modal, you can either select an existing open invoice to move the time logs to, or create a new invoice for them.
For more information, see: Logging time in the time area of a project