Use Total Slack field to report project behind schedule

If you want to know whether how many days your project is behind schedule showing in the Total Slack field, you should:

1. Double-click the last task or the finish milestone to open the Task Information dialog box.
2. In the Advanced tab:enter the finish date in the Deadline field and select as late as possible in the Constraint type field and then click on the OK button.
3. You will notice a down-arrow sign appears in the Bar Chart area.

4. Save it as baseline.

5. Then use it to track the actual progress.

6. The image above shows the result.