Average using multiple criteria with start and end date

I'm not sure your data is organized in the most convenient manner given your objectives. It'd probably be easiest to track billability for everyone on a daily basis, which would be much easier than your start and end dates when it comes to calculating monthly percentages. Can you reorganize the data (or do you possibly have it on a daily basis elsewhere)?

Thanks for the reply, however we dont have a daily track of billability/non bill. we just have a start date and end date to show

I just need the following criteria to be looked at in the 2nd sheet:
1. Column C (billable/ non-billable)
2. end date and start date
3. column BC

I tried the averageifs with ">= [date]" and "<=[date]" criteria but its not working.

Do you have any suggestion on how to go about with this?

appreciate your help.