Help in Cumulative Total

Hi apatwal 
Here is the updated file https://www.dropbox.com/t/l8yJiCeJNMa9ItgD
Again you are right. And again I shifted all calculations down to day level in order to obtain correct results dynamically regardless on which level slicing is. Changes are mainly in the last year margin measure. However following you can find the code of all measures and calculated columns
Day Rank column in the date table:

Day Rank = 
RANKX ( 
    'Date',
    'Date'[Date],,
    ASC
)

Then the measures are

Total Margin = SUM ( 'Margin data'[Margin] )

ShowValueForDates = 
VAR LastDateWithData =
    CALCULATE ( 
        MAX ( 'Margin data'[Invoice Date] ), 
        REMOVEFILTERS () 
    )
VAR FirstDateVisible =
    MIN ( 'Date'[Date] )
VAR Result = 
    FirstDateVisible <= LastDateWithData
RETURN
    Result

Margin Same Period Last Year = 
IF (
    [ShowValueForDates],
    VAR FirstDayRanknPeriod = 
        CALCULATE ( 
            MIN ( 'Date'[Day Rank] ),
            'Date'[DateWithData] = TRUE ()
        )
    VAR LastDayRankInPeriod = 
        CALCULATE ( 
            MAX ( 'Date'[Day Rank] ),
            'Date'[DateWithData] = TRUE ()
        )
    RETURN
        CALCULATE (
            [Total Margin],
            REMOVEFILTERS ( 'Date' ),
            'Date'[Day Rank] >= FirstDayRanknPeriod - 364,
            'Date'[Day Rank] <= LastDayRankInPeriod - 364
        )
)

Difference in Margin = 
VAR CurrentYear =
    MAX ( 'Date'[Year] )
VAR CurrentYearMargin =
    CALCULATE (
        [Total Margin],
        'Date'[Year] = CurrentYear
    )
VAR MarginLastYear = 
        [Margin Same Period Last Year]
RETURN
IF ( 
    NOT ISBLANK ( MarginLastYear ),
    CurrentYearMargin - MarginLastYear

Margin Diff Cumulative = 
VAR LastDayInFilter =
    MAX ( 'Date'[Day Rank] )
RETURN
IF ( 
    [ShowValueForDates],
    CALCULATE ( 
        [Difference in Margin],
        REMOVEFILTERS ( 'Date' ),
        'Date'[Day Rank] <= LastDayInFilter
    )
)