Hi, I'm late to the party, but it is never to late for me to address my favorite topic. I believe, assuming Steemit user is a US citizen - when the Steem currency (any of the three but there is some debate on Steem Power) is credited to his/her account for posting/curating, it is treated as property they received and is taxable at that point in time). See Notice 2014-21 Q-3, 5,10. He/She will then begin a holding period and if they convert to USD after a year, will be taxed long-term capital gains (or a loss) on the difference between the USD proceeds and the value when he/she received the crypto. The good news is, he/she may have also potential expenses that are now business expenses. This will be the subject of one of the many topics I am covering in my tax blog, and I am going to have examples and helpful suggestions for the filing season that is upcoming.

PS: I will research whether it is appropriate to classify the Steem Power as restricted property, or that it falls outside scope of cryptocurrency from the perspective of the Notice, but I will have more in depth analysis later on.

This is not tax advice to any one individual and shouldn't be used to attempt to avoid taxes/penalties.