The easiest way is using two different worksheet and join as dashboard to show last two months with delta.
If you show last two months in one worksheet, November's delta column also show the delta from October.
In below case, sheet 3 is filtering o and 1 in last() filter and sheet 2 filters only 0 in last() filter.
Last_two_months+9.2.twbx 1.1 MB
Thank you for your reply Shin.
But your way isn't really solving my problem. I want the percent difference to change as user changes date filter. Basically what I want is when user chooses December 15 then the view shows actuals and percent difference of december and november.