Thanks Niek, that is exactly what I needed to achieve.
Enjoy your day,
deb

"Niek Otten" wrote:

Maybe:

=IF(C1="",B1-A1,C1-A1)

Format as number, not as date

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Kind regards,

Niek Otten
Microsoft MVP - Excel

"dhealy" wrote in message
...
I have 3 columns with dates in them with one column being the constant. I
need to find the number of days between the constant date and one column
if
the other column is blank, if there is a date in the 3rd column then I
need
to use that date with the constant. Help...