Hello Pavat,
Sorry for the mismatch. I did a confusion between [LY] and [CY].
So you want to add 8 month to Last Year and subtract 4 months to Current Year.
So the formula will be:
=If(MonthNumberOfYear([Key Date])<4
;FormatDate(RelativeDate([Key Date]; -125);"yyyyMM")
;FormatDate(RelativeDate([Key Date]; -120);"yyyyMM"))
In the first part of the expression, you add 8 months to Last Year: -365 + (8 * 30) = -125
In the second part of the expression, you subtract 4 months to Current Year: 30 * 4 = 120 + 365 = -120
Didier