The end date on the offer letter is pre-populated by the Target End Date field on the job requisition.  Unfortunately, the date on the requisition when it is created is typically NOT the actual end date for the hire. For the staff offer letter the user can edit that date before sending the offer letter to the candidate.  The student offer letter is not editable in the generate document step, like the staff letter is.  So in these instances, it's easier to just correct the req for them and update the date and then trigger the regenerate offer letter task.