While creating batch invoices or manual invoices from approved time and expense entries, you can exclude some entries from the current billing session, but still keep them in work-in-progress. Or you can mark them as billed and remove them from work-in-progress and future processing of invoices. You can create invoices and exclude time or expense entries from them. To do so:

1. Open the Invoices screen from the main menu > Billing. 
2. Create a new batch invoice and enter the appropriate information on the Invoice Filters and Options dialog before clicking Continue.
3. On the Create Batch Invoice screen, open the row-action menu and click Billing Details.
4. The Invoice Details dialog displays the Time Details, Expense Details, and Billing Details. Select the appropriate tab and after selecting the appropriate entries on the grid, select Actions > Exclude (or Mark Billed, if needed).
5. Click Save. 

The selected entries are excluded from billing! Check CORE Help Center for details.