How to make multiple formula criteria hierarchical

[dougalf]

I am trying to output either TRUE or FALSE and apply conditional formatting based on that output. But I'm struggling with how to arrange this in regard to boolean operators and syntax.

Condition 1: Date in column A is no further back than 15 days from today
Condition 2: Value in column B appears 3 times or more in column B

I want output from my formula to be true if and only if condition 1 is met. So condition 2 should only be checked if the other entries fall within the date range.

Please look at the attached screenshot. Column C is just a test so I can see if the output of the formula is what I want it to be before I make it a new conditional formatting rule. Obviously my formula is failing, as you can see by the TRUE value next to 3311, which only appears twice within the specified date range (run date was 12/8/2020). I know why it's failing, but I don't yet know how to fix it by nesting or whatever.

TIA for your help

[dougalf]

I have tried applying both criteria in the conditional formatting stack one at a time, with the Stop checkbox checked if the date is NOT within the specified range. But that didn't work either.

I'm just starting out with conditional formatting, so I'm unsure on how stacking them works.

[JeteMc]

Hello dougalf and Welcome to Excel Forum.
Try (untested): =and(a2>=today()-15,countifs(B:B,B2,A:A,">="&today()-15)>=3)
If that doesn't work please utilize the instructions in the banner at the top of the page to upload an .xlsx file
Let us know if you have any questions.