@sean-king, that's interesting... seems to me you're supposing SBD and Steem to be "currency" rather than an "asset class" or "property" here.
To that end, I'm pretty sure the IRS treats cryptocurrencies as "property." True, property can be taxable under certain circumstances... but let's remember we are not employees of Steemit; we are also not "independent contractors" which require an agreement that some non-employee service is provided in exchange for remuneration. No such condition exists here... when I make a post, I may or may not end up with a reward-- we have zero contractual agreements. An exception might be something like "steemgigs" where there IS an arrangement to receive "compensation" for a "service;" or when an artist uses "steemshop" to sell a piece work... even that is a bit dodgy, though.
If we really stretch reality a bit, we could argue what we get here are "gifts," but it's not (technically speaking) Steemit giving us gifts... it's a network of thousands of individuals throwing a few cents in our tip jars. Since the IRS exemption for reporting gifts is $14,000 for the giver, not the recipient... that would get pretty nebulous to track.
But we are getting something of value, however. It seems most likely that we are getting an "asset" in which our cost basis (at the rime of receipt) is zero, assuming we are only talking rewards here, not actually buying Steem and powering up. We'll assume these are assets held for gain... not like a painting we're just going to hang on the wall... meaning we do have to keep track.
So that puts us over in a similar asset class to collectibles... all we have is a "thing" in which we have a cost basis, and the next action that triggers a taxable event is the sale of that asset... presumably for a gain. But until we actually sell the asset, all we have is an unrealized gain.
Just like the IRS isn't going to come around to my house and say "we think your stamp collection went up in value by $4000 in 2006, so you owe taxes," or even less likely "your house value went up $10000 this year, so you owe taxes!" I would imagine something similar would apply to cryptocurrencies until the IRS changes their classification to "financial instrument" or "currency."
But when you sell your Steem... then you trigger a taxable event. You now have a capital gain (presuming you've held your Steem for at least a year) or a short term capital gain (less than 12 months-- taxed as ordinary income) on what you sold. Only.
Bottom line... under current rules, it doesn't seem to me any taxable events are triggered till we actually turn our cryptos into fiat.
You must not have read all my prior comments. Please go back and do so. The law is clear, and it doesn't matter whether SBD and SP are considered property or currencies, the tax effects are the same.
As I indicated in prior comments, if (for instance) you find a treasure of one-of-a-kind ancient artifacts (that is, property) in your back yard, you must must pay tax on the fair market value of that property as of the day you found it, and you must make a good faith effort (including hiring appraisers if necessary) to determine that fair market value. The property is taxed at its fair market value in the year you found it even if you never sell the property but instead just hold it. Furthermore, the value of the property is considered ordinary income and taxable at ordinary income rates. The fair market value on the day you found it then becomes your tax basis in the property.
If you do later sell the property, then your taxable gain (or loss) is determined by subtracting the sales proceeds from your tax basis (that is, from the fair market value on the day you found it). And, any gain or loss would then be a capital gain/loss.
Again, then tax treatment of found property is not even a tough question. It's black and white law. You'll find numerous examples here: https://www.google.com/search?q=if+I+find+treasure+is+it+taxable&rlz=1C9BKJA_enUS677US679&oq=if+I+find+treasure+is+it+taxable&aqs=chrome..69i57.4504j0j4&hl=en-US&sourceid=chrome-mobile&ie=UTF-8
So again, it doesn't matter whether SBD/SP is considered a currency or property, the tax treatment is the same.