% diff 2 values

Hi M_SBS_6 

Maybe you can try this:

I create a set of sample data:

Then create a measure:

DIFF = 
	VAR _currentMonth = MONTH(MAX('Table'[date]))
	VAR _currentYear = YEAR(MAX('Table'[date]))
	VAR _PreviousYear = CALCULATE(
		YEAR(MAX('Table'[date])),
		FILTER(
			ALLSELECTED('Table'),
			YEAR('Table'[date]) < _currentYear
		)
	)
	VAR _perviousValue = CALCULATE(
		SUM('Table'[value]),
		FILTER(
			ALLSELECTED('Table'),
			YEAR('Table'[date]) = _PreviousYear && MONTH('Table'[date]) = _currentMonth
		)
	)
	RETURN
		IF(
			_perviousValue <> BLANK(),
			(_perviousValue - SUMX(
				'Table',
				'Table'[value]
			)) / _perviousValue
		)

The result is as follow:

Best Regards,

Zhengdong Xu

If this post helps, then please consider Accept it as the solution to help the other members find it more quickly.