Hi Brian Trust 
I am needing a date formula that is a bit over my head 
So  IF Jan Due is a date then subtract Jan actual from Jan Due date (using Jan Variance column)
 BUT if Jan Due date is blank report a blank 
AND if Jan Actual Date is not a date then report "OVERDUE" in the Jan Variance Column
I have so far but is not working 
=IF(ISBLANK([Jan Due Date]@row), "", IF(ISDATE([Jan Due Date]@row), IF(ISDATE([Jan Actual Date]@row), [Jan Due Date]@row - [Jan Actual Date]@row,) "", "OVERDUE")))))