SUMMARIZE DAX help needed

Hi thampton 

It seems you import data into Power BI.

If so, assume [sale id] in Sales table and [sale id] in financials table have "many to one" relationship

In  Sales table

Create calculated columns

year = YEAR('Sales table'[date])

month = MONTH('Sales table'[date])

Create measures

sales_monthly =
CALCULATE (
    SUM ( 'Sales table'[sales] ),
    FILTER (
        ALLSELECTED ( 'Sales table' ),
        'Sales table'[year] = MAX ( 'Sales table'[year] )
            && 'Sales table'[month] = MAX ( 'Sales table'[month] )
            && 'Sales table'[sales id] = MAX ( 'Sales table'[sales id] )
    )
)

Max sales =
MAXX (
    FILTER (
        ALLSELECTED ( 'Sales table' ),
        'Sales table'[sales id] = MAX ( 'Sales table'[sales id] )
            && 'Sales table'[year] = MAX ( 'Sales table'[year] )
    ),
    [sales_monthly]
)

Best month =
CALCULATE (
    MAX ( 'Sales table'[month] ),
    FILTER (
        ALLSELECTED ( 'Sales table' ),
        'Sales table'[sales id] = MAX ( 'Sales table'[sales id] )
            && 'Sales table'[sales_monthly] = [Max sales]
    )
)

Best Regards
Maggie

Community Support Team _ Maggie Li
If this post helps, then please consider Accept it as the solution to help the other members find it more quickly.