Average selected month

Hi,  powerbi1986
You could create measures like the following:

average after =
AVERAGEX(
    FILTER(
        ALLSELECTED( 'table' ),
        'table'[month] > SELECTEDVALUE( 'table'[month] )
    ),
    [value]
)

average before =
AVERAGEX(
    FILTER(
        ALLSELECTED( 'table' ),
        'table'[month] <= SELECTEDVALUE( 'table'[month] )
    ),
    [value]
)

Or, please share your sample pbix file's link here, then I can try to look into it to come up with a more accurate measure.

Best Regards,
Community Support Team _ Zeon Zheng

If this post helps, then please consider Accept it as the solution to help the other members find it more quickly.