Goal: Shift the date context to compare against specific past or future periods.
DATEADD is the "Time Machine" of DAX.
Ready...
💻 DAX Formula
-- Scenario 1: Previous Month (PM)
MEASURE Sales PM =
CALCULATE (
SUM( Sales[Amount] ),
DATEADD( 'Date'[Date], -1, MONTH )
)
-- Scenario 2: Next Month (Projection)
MEASURE Sales NM =
CALCULATE( SUM(Sales[Amt]), DATEADD(..., 1, MONTH) )