Thank you, abctax55.  I updated the software first in case that was the issue.  And the only returns showing an incorrect due date are those with a fiscal year ending in September.  I know all my charts show the true due date is 1/15/19, but it is still reassuring that your software shows that date also.  I wouldn't know where to even attempt to override the due date, but there is nothing indicated in either the penalty or misc screens.