Solution 1
	startDatePreviousMonth = DATEADD(mm,-1,startDate)
	endDatePreviousMonth = DATEADD(dd,-1,startDate)
	startDatePreviousYear = DATEADD(yy,-1,startDate)
	endDatePreviousYear = DATEADD(dd,-1,DATEADD(mm,-11,startDate))

Solution 2
	SET @startDatePreviousYear = CAST(DateAdd(yy,-1,@startDate)AS DATE)
	SET @endDatePreviousYear = CAST(DATEADD(dd,-1,DATEADD(yy,-1,DATEADD(dd,1,@endDate)))AS DATE)
	SET @startDatePreviousMonth = CAST(DateAdd(mm,-1,@startDate)AS DATE)
	SET @endDatePreviousMonth = CAST(DATEADD(dd,-DAY(@EndDate),@endDate)AS DATE)