Formula to substitute monthly values

[Peter_Yaacoub]

Hellooo PBI experts!

I have done the ETL process on a Balance Sheet for a group companies where the current month is compared to December of last year (i.e. Jan 2022 vs Dec 2021; Feb 2022 vs Dec 2021; etc.).

I need help with a function so that when February comes and the query is refreshed,  December 2021 values from January table are removed and replaced with December 2021 values from February table.

Your help is much appreciated.

[amitchandak]

@Peter_Yaacoub , The flag you wanted is not clear.

You can get last year last month for selected value

last year last month = CALCULATE(SUM(Sales[Sales Amount]),DATESMTD(dateadd('Date'[Date],-1*month(Today()),MONTH)))

Last year last month based on today =
var _max= eomonth(today(),-1*month(Today()))
var Min= eomonth(_max,-1)+1 
return
CALCULATE(sum('Table'[Qty]), FILTER(ALL('Table'),'Table'[Date] >= _min && 'Table'[Date] <=_max ) )