Add Previous Period (year) based on a custom date range selection

Hi  ATO23 ,

I created some data:

Here are the steps you can follow：

1. Create measure.

Flag =
var _select=SELECTEDVALUE('Period'[RelativeDate])
var _date=CALCULATE(MAX('Period'[Date]),FILTER(ALL(Period),'Period'[RelativeDate]=_select))
return
IF(
AND( MAX('Table'[Year])=YEAR(_date),MAX('Table'[Month])=MONTH(_date))||AND(MAX('Table'[Year])=YEAR(_date)-1,MAX('Table'[Month])=MONTH(_date))
    ,1,0)

Measure =
SUMX(
   FILTER( ALLSELECTED('Table'),'Table'[Year]=MAX('Table'[Year])&&'Table'[Month]=MAX('Table'[Month])),[amount])

2. Place [Flag]in Filters, set is=1, apply filter.

3. Result:

Best Regards,

Liu Yang

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