Percentage Change using DAX

Date		In Month Actual
31/01/2023	2,590,446.12
31/01/2023	47.40
31/01/2023	58.20
31/01/2023	38,471.94 
31/01/2023	7,557.15 
31/01/2023	6,870,250.38
31/01/2023	73,325.34 
31/01/2023	5,754.04
31/01/2023	1,270,666.30 
31/01/2023	426,068.41 
28/02/2023	161.36 
28/02/2023	7,557.15
28/02/2023	5,754.03
28/02/2023	426,068.78 
28/02/2023	161.36 
28/02/2023	7,557.15
28/02/2023	5,754.03
28/02/2023	426,068.78
28/02/2023	5,754.03
28/02/2023	426,068.78
31/03/2023	161.36
31/03/2023	38,026.78
31/03/2023	3,444.45 
31/03/2023	779,195.00
31/03/2023	1,145,854.33 
31/03/2023	26.88 
31/03/2023	1,078,846.04 
31/03/2023	7,626.63
31/03/2023	402,275.36 
31/03/2023	1,021,696.88

how do i calculate percentage in power bi over three months?

I have written this DAX formular but its doesn't seem to work:

InMonthActualPercentageChange =

VAR CurrentMonthValue = CALCULATE(SUM(A120[In Month Actual]), LASTDATE(A120[Date of Data]))

VAR PreviousMonthValue = CALCULATE(SUM(A120[In Month Actual]), DATEADD(LASTDATE(A120[Date of Data]), -1, MONTH))

First, create a separate date/calendar table.

Calendar = CALENDARAUTO()

Create a relationship between this and the date column of your data table.

Then change the date references in your measure to reference the 'Calendar'[date]. The DATEADD() function requires a date column with a contiguous interval.

Finally, add a RETURN expression after your two variables, something like so:

RETURN DIVIDE( CurrentMonthValue - PreviousMonthValue, PreviousMonthValue )

Using DIVIDE() instead of a "/" operator is a best practice because the function will handle division by zero by returning "Infinity" instead of an error.

---EDIT---

Put a Month column on your Date table, and use that in your visual (e.g., Month = EOMONTH('Date'[Date],0) to get the last day of the month). Additionally, the DATEADD() function shifts the date range passed to it. If you pass a single date, you get a single date. May be better to pass the whole month to both.

For current month, use this in place of LASTDATE()

DATESINPERIOD('Date'[Date],LASTDATE('Date'[Date]),-1,MONTH)

And for prior month shift that back one month. The whole measure would then look like this:

InMonthActualPercentageChange =
VAR BasePeriod = DATESINPERIOD( 'Date'[Date], LASTDATE( 'Date'[Date] ), -1, MONTH )
VAR CurrentMonthValue =
    CALCULATE ( SUM ( A120[In Month Actual] ), BasePeriod )
VAR PreviousMonthValue =
    CALCULATE (
        SUM ( A120[In Month Actual] ),
        DATEADD ( BasePeriod , -1, MONTH )
    )
RETURN
    DIVIDE ( CurrentMonthValue - PreviousMonthValue, PreviousMonthValue )

This forces the examination period to always be one month over one month.