Power Bi DAX: Relative Date Filtering

Question

I have a quick question, is there a way to filter data from set days between 2 months?

Eg filter from 16-15 of Jan-Feb.

Is this possible?

For example i have used a measure to calculate days between dates

Last Assessment 16-15 
    = CALCULATE(SUM('Table1'[Duration1]),'Table1'[Start], 
             DATESBETWEEN('Calendar'[Date], [Assessment Date], [Assessment one month]))

Assessment Date = if(DAY(TODAY())<16,DATE(YEAR(TODAY()),MONTH(TODAY())-1,15),
                      DATE(YEAR(TODAY()),MONTH(TODAY()),15))

Assessment one month = EDATE([Assessment Date],-1)+1
Assessment 6 = EDATE([Assessment Date],-6)+1
Assessment 12 = EDATE([Assessment Date],-12)+1

The last assessment does show from the 16th of 2 months ago to last months 15th eg Dec 16th - Jan 15th. But i need to show from last 6 months and the last 1 year.

How can i work this out so i can show the Last 6 months and 1 year.

So far i have had to use a date filter to manually select the dates which i want to stop and have it be automatic.

Answer 1

If it is just the last 6 months or the last year you could make a custom column in the query editor (this would be the easiest way then). Like a filter flag:

'Includes the current month
Last 6 Months Flag = Date.IsInPreviousNMonths([YourDate], 6) or Date.IsInCurrentMonth([YourDate])

'Without the current month
Last 6 Months Flag = Date.IsInPreviousNMonths([YourDate], 6)

The same for last year:

Last Year Flag = Date.IsInPreviousYear([YourDate])

Drag and drop these custom columns as filter on your report and you are done.

Answer 2

consider following measure for Latest assessment (basically what you had before with EDATE for safe Dec/Jan handling and with variables for better performance)

Latest Assessment Date = 
VAR __today = TODAY()
RETURN
IF (
    DAY ( __today ) < 16,
    DATE ( YEAR ( __today ), MONTH(EDATE(__today, - 1)), 15 ),
    DATE ( YEAR ( __today ), MONTH ( __today ), 15 )
)

then you have this measure for handling 1/6/12 scenarios, you just replace 12 with whatever number of months you need

Measure 12 =
VAR __nrOfMonthsBack = 12
VAR __lastAssesment = [Latest Assessment Date]
RETURN
    CALCULATE (
        SUM ( Table1[Duration] ),
        ALL('Calendar'),  --this will reset any date filters coming from slicers
        DATESBETWEEN (
            'Calendar'[Date],
            EDATE ( __lastAssesment, - __nrOfMonthsBack ) + 1,
            __lastAssesment
        )
    )

EDIT: added ALL('Calendar') to disable filters coming from slicers