SUM of current and every previous month minus same month last year

[annae]

I need to do this: for every current period, sum all last periods' (if they exist) plus the current's period value. Moreover, I have to exclude from the result, the value of the same month (to the current) from the last year. 

Example: 

November 2017 = (the values of all months until October 2017) + November's 2017 - November's 2016

Help me please !! 🙄

[parry2k · Accepted solution]

@annae As a best practice, add date dimension in your model and use it for and time intelligence calculations. Once the date dimension is added, mark it as a date table on table tools.

https://perytus.com/2020/05/22/create-a-basic-date-table-in-your-data-model-for-time-intelligence-ca...

And you can add this measure once date dimension is in the model

Total = 
CALCULATE ( SUM ( Table[Amount] ), DATESYTD ( DateTable[Date] ) ) -
CALCULATE ( SUM ( Table[Amount] ), SAMEPERIODLASTYEAR ( DateTable[Date] ) ) 

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