how to pass on multiple slicer values dynamically to DAX IN operator

[smpa01]

My source data is following

| Year | month | val |
|------|-------|-----|
| 2020 | 1     | 100 |
| 2020 | 2     | 200 |
| 2020 | 3     | 300 |
| 2020 | 4     | 400 |
| 2020 | 5     | 500 |
| 2020 | 6     | 600 |
| 2020 | 7     | 700 |
| 2021 | 1     | 400 |
| 2021 | 2     | 500 |
| 2021 | 3     | 600 |

I have a viz like following

All I want is

DAX to

     return sum=300 for all rows

    when

    Year=2020 and Month=1,2

   and

     return sum=600 for all rows

    when

    Year=2020 and Month=1,2,3

 and so on and so forth

My desired result is following

which I can achieve if I write a measure like following

Measure = CALCULATE(SUM('Table'[val]),ALLEXCEPT('Table','Table'[Year]),'Table'[month] IN {1,2})

But I was wondering , is there a way to pass on the slicer selections to IN dynamically, cause when I select month=1,2,3 the measure falls flat

As much as I want to know if there is way to pass on the slicer selections to IN, if there is another way that can give me the end result, I would be interested in that too.

The desired result is following

DAX to filter the table as per the slicer selection and perform an ALL within the subset returned by slicer, so that it returns the following

 pbix is attached

Thank you in advance

@AlexisOlson 

[AlexisOlson · Accepted solution]

I'd recommend using ALLSELECTED with a variable:

VAR SelectedMonths = ALLSELECTED ( 'Table'[month] )
RETURN
    CALCULATE (
        SUM ( 'Table'[val] ),
        'Table'[month] IN SelectedMonths
    )

You could also write it like this:

VAR SelectedMonths = ALLSELECTED ( 'Table'[month] )
RETURN
    CALCULATE (
		SUM ( 'Table'[val] ),
		TREATAS ( SelectedMonths, 'Table'[month] )
	)

[smpa01]

Awesome @AlexisOlson !! Thanks a lot