Calculating the difference between dates in the same column

Hello Anonymous 

We jsut need a couple date tables, one inactive relationship and the right measure.

Notice that the relationship between Dates 2 in the data is inactive.  We will turn it on in our mesure when needed.  We can get a simple date table with this DAX

Dates 1 = 
VAR DateRange = CALENDARAUTO()

RETURN 
ADDCOLUMNS(
    DateRange,
    "Year",YEAR([Date]),
    "Month",FORMAT([Date],"mmmm"),
    "Year Month", FORMAT([Date],"yyyy-mmmm"),
    "YearMonthSort",YEAR([Date])*100 + MONTH([Date]),
    "ShortName",FORMAT([Date],"ddd"),
    "IsWeekDay", NOT WEEKDAY( [Date] ) IN {1,7}
)

Dates 2 is just this.

Dates 2 = 'Dates 1'

Amount 1 is straight sum using the first date relationship.

Amount 1 = SUM ( Data[Amount] )

Amount 2 is where we turn off the relationship with the first date table and turn on the link with the second one.

Amount 2 = 
CALCULATE(
    SUM ( Data[Amount] ),
    CROSSFILTER ( Data[Date], 'Dates 1'[Date], None), // Turns off the link to Dates 1
    USERELATIONSHIP ( Data[Date], 'Dates 2'[Date] ) // Turns on the link to Dates 2
)

Then the profit measure

Profit = [Amount 2] - [Amount 1]

And we get out desired result.

I have attached my sample workbook for you to look at.