How about just checking if the month in question is December and if so, returning 0 instead of the previous month?
VAR vLastMonth =
CALCULATE(
EOMONTH(MAX(DateTable[Date]), -1),
ALLSELECTED(DateTable[Date])
)
RETURN
IF(
MONTH(vLastMonth) = 12,
BLANK(), // Return 0 instead if you'd like
CALCULATE( // Rest of your measure goes here