YoY Growth % DAX Formula

Hi Trying2Excel , Thank you for reaching out to the Microsoft Community Forum.

Try below:

YoY Growth Rate =

VAR _currentYear = SELECTEDVALUE('Historical Reductions Table'[End of Month].[Year])

VAR _previousYear = _currentYear - 1

VAR _currentMonth = MONTH(MAX('Historical Reductions Table'[End of Month]))

VAR _currentYearReduction =

    CALCULATE(

        SUM('Historical Reductions Table'[Reduction2]),

        FILTER(

            ALLSELECTED('Historical Reductions Table'),

            YEAR('Historical Reductions Table'[End of Month]) = _currentYear

            && MONTH('Historical Reductions Table'[End of Month]) <= _currentMonth

        )

    )

VAR _previousYearReduction =

    CALCULATE(

        SUM('Historical Reductions Table'[Reduction2]),

        FILTER(

            ALLSELECTED('Historical Reductions Table'),

            YEAR('Historical Reductions Table'[End of Month]) = _previousYear

            && MONTH('Historical Reductions Table'[End of Month]) <= _currentMonth

        )

    )

RETURN

    IF(

        ISBLANK(_previousYearReduction) || _previousYearReduction = 0,

        BLANK(),

        DIVIDE(_currentYearReduction - _previousYearReduction, _previousYearReduction)

    )

If your End of Month column has a date hierarchy, you can replace YEAR('Historical Reductions Table'[End of Month]) with 'Historical Reductions Table'[End of Month].[Year]' and similarly for MONTH

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Thank you.