Cumulative total in fixed period

Hi,

According to your description, i create a sample to test:

Please follow these steps:

1)Create a slicer table:

Slicer Table = DISTINCT(SELECTCOLUMNS('Table',"Month",'Table'[Date].[Month],"MonthNo",'Table'[Date].[MonthNo]))

2)Try this measure:

Measure = 
IF (
    MAX ( 'Table'[Month] ) = SELECTEDVALUE ( 'Slicer Table'[Month] ),
    MAX ( 'Table'[Monthly Value] ),
    CALCULATE (
        SUM ( 'Table'[Monthly Value] ),
        FILTER (
            ALLSELECTED ( 'Table' ),
            'Table'[Date] <= MAX ( 'Table'[Date] )
                && 'Table'[Date]
                    >= IF (
                        MIN ( 'Table'[MonthNo] ) < MIN ( 'Slicer Table'[MonthNo] ),
                        DATE ( YEAR ( MIN ( 'Table'[Date] ) ) - 1, MIN ( 'Slicer Table'[MonthNo] ), 1 ),
                        DATE ( YEAR ( MIN ( 'Table'[Date] ) ), MIN ( 'Slicer Table'[MonthNo] ), 1 )
                    )
        )
    )
)

3)Create a check measure:

check = 
IF (
    MAX ( 'Table'[Date] )
        < DATE ( MINX ( ALLSELECTED ( 'Table' ), 'Table'[Date].[Year] ), CALCULATE (
            MAX ( 'Slicer Table'[MonthNo] ),
            FILTER (
                'Slicer Table',
                'Slicer Table'[Month] = SELECTEDVALUE ( 'Slicer Table'[Month] )
            )
        ), 1 ),
    0,
    1
)

4)Choose above [Measure] and [Year],[Month],[Monthly Value] as a table visual.

   Apply the above [check] to this visual by setting [check]=1.

   Choose [Month] from slicer table as a slicer.

   When select one month in slicer, the result shows:

Here is my test pbix file:

pbix 

Hope this helps.

Best Regards,

Giotto Zhi