How to add an Expense to an Invoice
You can associate the expense to a time card on your time sheet or when the popup time card appears. If you do not have time that can be associated with the expense or do not wish to associate the expense to a specific time card, you can create a “zero” amount time card and add the expense to it.
Once a time card has been added to an invoice, any expense associated to this time card will be added to the invoice automatically. You can also add an expense to an invoice without it having to be associated to a time card by clicking in the expense field on the invoice and selecting the override option.