Re-open a closed period

If you need to re-open a closed period, you will have to undo all calculations for all the periods after the one you need to re open. For example, if the system is currently in April 20XX, and you need to go back to January, you should undo calculations for April, March and February of the corresponding Fiscal Year. 

To do this:

1. Express > Results > Run Calculations

2. Show Steps>Made a Mistake > Undo All Steps

3. After the results have been deleted and the checkmark next to "Results" shows a gray checkmark, go back to the admin tool in SFDC and click "Delete Results", then click on "Unclose Period"

Repeat this process (steps 1,2,3) until you're in the period you want to re open.