Calculating QTD is not working as expected. (DAX)

Thankyou, This got me to where I needed to be. For reference here is the final formula:

Capacity - This Quarter = CALCULATE(
    VAR LastDayOfQuarter =  EOMONTH ( TODAY(), 2 - MOD ( MONTH ( TODAY() ) - 1, 3 ) )
    VAR FirstDayOfQuarter = DATE ( YEAR ( TODAY() ), ROUNDUP ( DIVIDE ( MONTH ( TODAY() ),3 ),0 ) *3 -2, 1)
    VAR results = [Capacity]((DATESBETWEEN(DateDim[Date],FirstDayOfQuarter,LastDayOfQuarter)))
    RETURN
    results
)

Does this work too?

Capacity - This Quarter =
VAR ThisYear = YEAR ( TODAY () )
VAR ThisQtr  = QUARTER ( TODAY () )
RETURN
    CALCULATE (
        [Capacity],
        FILTER (
            ALL ( DateDim ),
            YEAR ( DateDim[Date] ) = ThisYear &&
            QUARTER ( DateDim[Date] ) = ThisQtr
        )
    )