If you do not, you can create one based on your spending records from previous months in each category. (elfi.com)
That insight deserves its own thread Monthly interest is from last day of previous month to 2nd last day of month. (highinterestsavings.ca)
For example I'm trying to run regularly but sometimes I get lazy... So I'm checking my stats and comparing with previous months. (thecollegeinvestor.com)