PARALLELPERIOD Returns a table that contains a column of dates that represents a period parallel to the dates in the specified dates column, in the current context, with the dates shifted a number of intervals either forward in time or back in time.
Syntax
PARALLELPERIOD(dates,number_of_intervals,interval)
Parameters
Dates – A column that contains dates.
Number_of_intervals – An integer that specifies the number of intervals to add to or subtract from the dates.
Interval – The interval by which to shift the dates. The value for interval can be one of the following: year, quarter, month.
Return Value
A table containing a single column of date values.
Reference Data
https://docs.microsoft.com/en-us/dax/dax-function-reference