If you are counting occurences then shouldn't you be using COUNTIF function...

Your formula is adding up the dates in the range F3:IU3 if date in D3:IS3 is
any date in the past six months or any date in future...
Then is substracting the sum of dates which are earlier than (hire date + 90
days). It will sum up even those dates which are earlier than hire date...

What do you really want? What do you want to achieve by summing dates?

"hmsawyer" wrote:

I have the following formula in place in a spreadsheet and have for the last
6 months. I just noticed a problem.

This formula is counting occurrences that have happened in the last 6 months
from TODAY(), but not counting anything that occurred in the first 90 days
from hire date, which is the beginning point in column A.

Now that some occurrences are 6 months old, the formula is counting those
that occurred in the first 90-days as a negative number. It should just not
count them at all, just as it did for the first 6 months they were listed on
the spreadsheet. Help! Thank you.

=IF($A3="",0,SUMIF(D3:IS3,"="&DATE(YEAR(TODAY()), MONTH(TODAY())-6,DAY(TODAY())),F3:IU3)-SUMIF(D3:IS3,"<"&($A3+90),F3:IU3))