Need help with Rolling Sum

Hi, Anonymous 

Try to create a measure like this:

Rolling Average Numerator =
VAR _sum12 =
    CALCULATE (
        SUM ( 'PowerBI(Index)'[Total Return Numerator ("calculated reutrn" tab, Column K)] ),
        FILTER (
            ALL ( 'PowerBI(Index)' ),
            EOMONTH ( 'PowerBI(Index)'[Return_id], 0 ) <= EOMONTH ( MAX ( [Return_id] ), 0 )
                && EOMONTH ( 'PowerBI(Index)'[Return_id], 0 )
                    > EOMONTH ( MAX ( [Return_id] ), -12 )
        )
    )
RETURN
    IF (
        HASONEVALUE ( 'PowerBI(Index)'[Return_id] ),
        _sum12,
        SUM ( 'PowerBI(Index)'[Total Return Numerator ("calculated reutrn" tab, Column K)] )
    )

my sample data:

Please refer to the attachment below for details

Hope this helps.

Best Regards,
Community Support Team _ Zeon Zheng
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