[DAX] Different between row based on column value

Hi  Anonymous ,

I created a sample pbix file(see attachment) for you, please check whether that is what you want. You can create a calculated column or measure as below:

calculated column:

Column = 
VAR _year =
    IF ( 'Table'[Month] = 1, 'Table'[Year] - 1, 'Table'[Year] )
VAR _month =
    IF ( 'Table'[Month] = 1, 12, 'Table'[Month] - 1 )
VAR _premreading =
    CALCULATE (
        SUM ( 'Table'[reading] ),
        FILTER (
            ALLSELECTED ( 'Table' ),
            'Table'[Level] = EARLIER('Table'[Level])
                && 'Table'[Year] = _year
                && 'Table'[Month] = _month
        )
    )
RETURN
    IF(ISBLANK(_premreading),BLANK(),'Table'[reading]-_premreading)

Measure:

consumption = 
VAR _curlevel =
    SELECTEDVALUE ( 'Table'[Level] )
VAR _curyear =
    SELECTEDVALUE ( 'Table'[Year] )
VAR _curmonth =
    SELECTEDVALUE ( 'Table'[Month] )
VAR _year =
    IF ( _curmonth = 1, _curyear - 1, _curyear )
VAR _month =
    IF ( _curmonth = 1, 12, _curmonth - 1 )
VAR _premreading =
    CALCULATE (
        SUM ( 'Table'[reading] ),
        FILTER (
            ALLSELECTED ( 'Table' ),
            'Table'[Level] = _curlevel
                && 'Table'[Year] = _year
                && 'Table'[Month] = _month
        )
    )
RETURN
    IF(ISBLANK(_premreading),BLANK(),SUM('Table'[reading])-_premreading)

If the above one can't help you get the desired result, please provide some sample data in your tables (exclude sensitive data) with Text format and your expected result with backend logic and special examples. It is better if you can share a simplified pbix file. You can refer the following link to upload the file to the community. Thank you.

How to upload PBI in Community

Best Regards