I am wanted to add similar functionality to the "Created On" Date column for my "Closed On" column. I want the date to automatically populate once I change status from Active or Pending to Closed, and want it to show once I save an item with this status change. Is this possible?
Use a SharePoint Designer workflow, started when the item is created, to wait for the item to be closed.
Wait for Status to equal Closed
Set Closed On to Today
You shouldn't use a calculated column, nor a workflow with an if statement, as some are suggesting. If the item is opened in edit mode any time after it's closed, and then saved (even if there are no changes) your Closed On value would change.