The reply I received suggested this formula...
=IF(COUNT(C1:D1),MAX(C1+90,D1+60),"")
Many thanks and I carefully tried it but did not completely work.
Maybe I confused the issue...
In column C, if there is a date in C1 or C2 or C3 or C4 and on down say thru
C30, I wish to add 90 days & have the date put in the corresponding E cell,
ie C20 answer in E20.

In column D, if there is a date in D1 or D2 or D3 or D4 and on down say thru
D30, I wish to add 60 days & have the date put in the corresponding E cell.

There would not be a date in C1 and D1 at the same time.
MANY MANY thanks for your help
David
This is a spreadsheet where we would enter a date in either C Or D column
vertically and have it automatically calculate the forward date in E column.