If you want to find out the work-in-progress (WIP) on your projects as of a specific date in the past, you can run the WIP Reconciliation report. On the Reports > Customize Report > Options tab, select the date range (Date From and Date To) for which you want to know the WIP and run the report. The required value is displayed under the Closing Billable WIP column. In contrast, if you want to see all the WIP of your projects as of today, run the WIP with AR report. Check CORE Help Center for more on running reports.