Filter Matrix on Percent Change

Hi All,
Firstly  parry2k thank you for your solution!
And DataFunness,For your question, you are trying to get the percentage you want based on last year's total sales, and this year's sales data from when you started until today, judging by the month selected, right?
For this question, here are some of our practical ideas we hope will help you!

ProRata_Sales_Percent_Change = 
VAR SelectedMonth = SELECTEDVALUE('Table'[Month])
VAR YearFraction = SelectedMonth / 12

-- Define last year's start and end dates
VAR LastYearStartDate = DATE(YEAR(TODAY()) - 1, 1, 1)
VAR LastYearEndDate = DATE(YEAR(TODAY()) - 1, 12, 31)

-- Calculate last year's total sales
VAR LastYearTotalSales = CALCULATE(
    SUM('Table'[Daily_Sales]),
    ALL('Table'),
    DATESBETWEEN('Table'[Date], LastYearStartDate, LastYearEndDate)
)

-- Define this year's start date and today's date
VAR CurrentYearStartDate = DATE(YEAR(TODAY()), 1, 1)
VAR CurrentDate = TODAY()

-- Calculate current year's year-to-date sales
VAR CurrentYearYTD = CALCULATE(
    SUM('Table'[Daily_Sales]),
    DATESBETWEEN('Table'[Date], CurrentYearStartDate, CurrentDate),
    REMOVEFILTERS('Table'[Month])
)

-- Calculate the ProRata percent change
RETURN
DIVIDE(CurrentYearYTD, LastYearTotalSales * YearFraction, 0)

Possibly our example data has limitations, there is no way to reproduce your negative number of cases, but the logic is unchanged, you can replace according to your actual situation, you want to filter their own data, you can filter the filter inside the filter, I hope that this idea will be helpful to you!

Hope it helps!

Best regards,
Community Support Team_ Tom Shen

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