Quote Originally Posted by Ace_XL View Post
=YEAR(EOMONTH(A2,-7))&"-"&YEAR(EOMONTH(B2,5))-1
Good call Ace, I think I was trying to overcomplicate the solution with, for example, "2006,2007,2008,2009" rather than "2006-2009"

I would have made a slightly different tweak though,

Formula: copy to clipboard
=YEAR(EOMONTH(A2,-7))&"-"&YEAR(EOMONTH(B2,-7))