The Add to Invoice panel appears on the right of the Invoice page when the customer has unbilled non-posting transactions. What is a non-posting sales transaction?
Depending on your company settings, this panel may include unbilled charges, expenses, and time.
To include unbilled transactions on a new invoice,select Add for each transaction you want to include. You can also:
Why are some extra charges shown?
Why are some charges missing from the invoice?
How do I avoid billing for a charge?