Hi Ankur,
Please provide HC for all the months to calculate the Annual Attrition.
Annualized attrition is term which is described to arrive at projected attrition on annual basis if this trend continues. In this current case you multiply the above with 12 and you get "Annualised attrition" This is projected figure only. If you are doing this month over month then you can take the past months actual data.
Lets take the example that we are computing in May 31st and calendar starts from Jan.
We Sum Avg people employed in Jan+Feb+Mar+Apr+May
Sum people left in Jan+Feb+Mar+Apr+May
apply the same formula but before multiplying with 12 divide by 5 to get annualised No.
You can get actual No. for last 12 months if you have data for last 12 month. When you have data for last 12 months, it is called "Annual Attrition". This is the figure of actual and did not have any projected element into this. For arriving at this you do not multiply with 12 as since you have the actual data for last 12 months.