Checking if record was the same in previous month

Hi All

I have a scenario relating to a Staff List, i have a list of staff that will be updated each month with the complete staff list as at that point in time. I categorise this with a DataDate field which in this case will be the 1st day of each month.

My scenario is that i want to be able to create either a Calculated column or measure that will tell me if that person transfered into that CostCentre for that month.  For example in the list below when looking at the data date of 1/1/2018 there are 6 staff 3 in cost centre ABC and 3 in DEF.  In the following month data date is 1/2/2018 we can see that there is now only 2 staff in ABC and 4 in DEF, i want to be able to show a flag or value that shows Alan Smith has transfered into cost centre DEF by looking back at the pervious month and seeing that his CostCentre was not equal to DEF but was actually ABC. 

I thought i could maybe user FILTER or SEARCH but am struggling to get the correct results.  This is a cutdown version of my staff list in order to simplify this, i have this data loaded in power bi desktop. 

Any help or advice is greatly appreciated

Thanks

Eddie