Datedif Formula????

Hello Gurus!!

I hope I can explain this like an educated person!!
I need some help creating one formula to calculate duration for periods of time, all with a start date and some with an end date. The duration column needs to display both duration of completed tasks and duration of ongoing tasks. My issue lies in the data without an end date. I need my third column (duration) to display the number of months from the start date to the current date, but update automatically when I re-open the file. At this time, I only need complete months, but I will be modifying the file later to display partial months.

completed task: end date - start date = duration

ongoing task: (I have a start date only) I would like this cell to update data automatically, rounding up to the next month. (eventually this will need to calculate months, weeks, & days - but not now)

I apologize if this is posted elsewhere. I have tried searching for similiar topics in the threads.

Thank you for any help.
Bosox76

See the attached workbook

You could change
=DATEDIF(A2,IF(B2="",TODAY(),B2),"m")
into
=MAX(DATEDIF(A2,IF(B2="",TODAY(),B2),"m"),1)

but the whole idea of "partial" months is unclear. Consider looking at days as well as months. See:

http://www.cpearson.com/Excel/datedif.aspx