You bring up a very, very important topic. @jerrybanfield recently covered this. Here is a couple links that might help:
(go to the last 1/3 of the video and he shows exactly how he's keeping track of his steemit earnings.)
https://steemit.com/steemit/@jerrybanfield/steemit-tax-calculation-and-payment-system
Here he goes into great detail about keeping records for taxes regarding Steemit.
I created a spread sheet and am keeping daily records as @jerrybanfield set forth.
Hope this helps as this is a very important topic that all Steemians need to keep track of. Great post and discussion! Resteemed
Thanks for the link! I'll check it out!