Compare Month to Month Data

Hi gmasta1129  ,

Thank you  for reaching out to the Microsoft fabric community forum.
Thank you vicky_ , for your response regarding the issue.

You can create the following DAX measure to calculate the NAV difference from the previous month for each Facility Code:

NAV Difference = 
VAR CurrentNAVDate = MAX('NAV_Data'[NAV Date])
VAR CurrentFacility = MAX('NAV_Data'[Facility Code])
VAR CurrentNAV =
    CALCULATE(
        SUM('NAV_Data'[Total NAV Value]),
        'NAV_Data'[Facility Code] = CurrentFacility,
        'NAV_Data'[NAV Date] = CurrentNAVDate
    )
VAR PrevNAVDate =
    CALCULATE(
        MAX('NAV_Data'[NAV Date]),
        FILTER(
            ALL('NAV_Data'),
            'NAV_Data'[Facility Code] = CurrentFacility &&
            'NAV_Data'[NAV Date] < CurrentNAVDate
        )
    )
VAR PrevNAV =
    CALCULATE(
        SUM('NAV_Data'[Total NAV Value]),
        'NAV_Data'[Facility Code] = CurrentFacility,
        'NAV_Data'[NAV Date] = PrevNAVDate
    )
RETURN
    IF(
        ISBLANK(PrevNAV),
        BLANK(),
        CurrentNAV - PrevNAV
    )

I tested it with my sample data, and it worked fine. Please find the attached screenshot and pbix for your reference.

If this helps solve your issue, kindly consider Accept it as a solution so other community members can find it useful too.
Reagrds,
Harshitha.