I'm sorry, I pasted exactly and got an error about mismatched parenthesis. From what I could tell, another ")" should be added at the very end, but I'm still getting the same error.
For the record, I think you had = instead of <>. I corrected the formula and changed for two year characters below. Thank you!!!
var text MM = Right(ToText (Month([Date])),2);
var text DD = Left(ToText(Day([Date])),2);
var text YY = If(Year([Date]) <> Year(Today()), Right(ToText(Year([Date])),2));
List("/", $MM, $DD, $YY))