Calculate Previous Month Value from Dynamic TTM Measure

Hi BunnyV ,

Maybe you can try to add an if statement to filter current and previous year based don selected calendar date:

_TTM =
VAR CurrentDate =
    MAX ( TTM[Date] )
VAR EndDate =
    MAX ( Calender[EOMONTH] )
VAR PreviousDate =
    DATE ( YEAR ( CurrentDate ), MONTH ( CurrentDate ) - 11, DAY ( CurrentDate ) )
VAR Result =
    CALCULATE (
        SUM ( TTM[VALUE] ),
        FILTER (
            ALLSELECTED ( TTM ),
            TTM[Date] >= PreviousDate
                && TTM[Date] <= CurrentDate
        )
    )
VAR MonthNo =
    CALCULATE (
        DISTINCTCOUNT ( TTM[Month] ),
        FILTER (
            ALLSELECTED ( TTM ),
            TTM[Date]
                >= DATE ( YEAR ( CurrentDate ), MONTH ( CurrentDate ) - 11, DAY ( CurrentDate ) )
                && TTM[Date] <= CurrentDate
        )
    )
VAR cYear =
    YEAR ( MAX ( calndar[Date] ) )
RETURN
    IF ( YEAR ( CurrentDate ) IN { cYear - 1, cYear }, Result / MonthNo )

Notice: add a visual filter to hide records who not contain correspond measure results.

Regards,

Xiaoxin Sheng