Trying to get the newest date if there are multiple rows

You could also just use this, array-entered with Ctrl-Shift-Enter:

=MAX(IF($A$1:$A$1000=A2,$T$1:$T$1000))

With newer versions, that would just be a regular formula:

=MAXIFS($T$1:$T$1000,$A$1:$A$1000,A2)

The check for count shouldn't be needed - this will work as well:

=AGGREGATE(14,6,N(+$T$2:$T$1000)/($A$2:$A$1000=$A2),1)

Originally Posted by XLent

Yes Bernie, but you're now performing a relatively expensive calculation when you don't need to.... not the best advice, tbh.

TBH - you're making some assumptions - that the values in A are not repeated. There is usually a reason for dating entries - because the other identifying values are repeated.

With no unique values in A, your formulas took 0.02053289 seconds - and mine took 0.01809833 seconds. So, that COUNTIF is the true "expensive calculation" - good thing I had a cup of coffee for the extra time I had to wait for yours to calculate

ha, yes, ok...

w/1000 unique values:

0.0625: w/pre-emptive COUNTIF*
0.1718: w/out pre-emptive COUNTIF

regardless of proliferation of dupes your challenge is more than fair -- COUNTIF(S) not always the most efficient when handling the used range intersect.

and obviously a little quicker still if the COUNTIF restricted to rows $2:$1000

And to be fair - to get anything meaningful from the OP's data set, a power query or Pivot Table would probably be a better approach - except the OP's version is 2010.

And I think that passing a limited range to COUNTIF doesn't matter - worksheet functions actually limit themselves to the used range, as opposed to Array-entered functions that use all rows.

I had not heard that about COUNTIFS - that's a big performance hit! My test showed it is 60X as long - Thanks for the tip!