=if(b4="",today()-b2,b4-b2)

The above assumes that your formula listed for B3 is a typo, as it would be
a circular reference. Also, you don't need Datedif to calculate the
difference in days -- simple subtraction will suffice.

Regards,
Fred.

"Simon2" wrote in message
...
In B2 i have a date 25/05/2008 the date an enquiry opened.
In B3 i have formula =DATEDIF(B3,TODAY(),"d")&" " this shows the days
elapsed since the enquiry opened.

I want to in B4 add the closure date of the enquiry, but then also as the
closure date is added have B3 stop counting, so the result shows the
number
of days to complete the enquiry in B3, so B3 would then =B4-B2 and the
rest
on Column 3 would continue to use the above formula until they were
closed.

Any ideas? I am using Excel2007.
Many Thanks
Simon