When you create an invoice for a customer, unbilled activities such as billable time and expenses appear in the Add to invoice panel. All unbilled activities for that customer appear in the panel, regardless of the Location field setting. You can add any unbilled activity to the invoice, no matter which Location you set on the invoice. This can be a problem if the Location on the invoice does not match the Location on the unbilled activity.
To solve this problem, create a separate invoice for each location, adding only the unbilled activities whose Location matches the Location on the invoice. To verify the Location of an unbilled activity before adding it to the invoice: