oooo... i love excel challenges

Do you have a lot of different conditions or just two? If it's just two, here goes:-

Let's say you have date 1 on cell A1, and date 2 on cell B1 (I.e, you want to make a condition based on the number of months date 2 is from date 1)

First you need a simple formula to count the difference in months which is this:-
=(MONTH(B1)-MONTH(A1))+((YEAR(B1)-YEAR(A1))*12)

Next to create the IF statement:-
=IF((MONTH(B1)-MONTH(A1))+((YEAR(B1)-YEAR(A1))*12)=10,"Action A",IF((MONTH(B1)-MONTH(A1))+((YEAR(B1)-YEAR(A1))*12)=20,"Action B","No condition matched!"))

Done!

datediff??

What is the syntax like, could you list it out?

Cool! Didn't know of such function.

Thanks for sharing!

that would give the difference in days, so won't work for this case.