Just to start off, I would like to point out that you can not currently trade STEEM for USD on any exchange, you can only trade them for Bitcoins.
In March 2014 the IRS made this announcement
https://www.irs.gov/uac/newsroom/irs-virtual-currency-guidance
But this was announced simply for the purpose of taxing Bitcoins, no laws were taken into consideration, they just basically said "People with Bitcoin have to pay Capital Gains tax, because we don't know how else to tax it". Now if you want to pay those taxes just to be on the safe side, go for it. But if you are willing to make a Federal Case out of it (Cryptocurrency is so new that no one has actually done this yet), here is the actual law regarding things like this:
US Constitution 16th Amendment:
The Congress shall have power to lay and collect taxes on incomes, from whatever source derived, without apportionment among the several States, and without regard to any census or enumeration.
USC Title 26 S 316:
(a) General rule
For purposes of this subtitle, the term “dividend” means any distribution of property made by a corporation to its shareholders
Now, when you receive STEEM, do you actually own any more of the website steemit.com than you did before you got STEEM? Can you get on an airplane and go look at the STEEM you have? If you own 51% of the STEEM available, do you now get to decide how Dan and Ned run the website? No. So according to USC Title 26 S 316, STEEM is not dividends.
USC Title 26 S 317:
(a) Property
For purposes of this part, the term “property” means money, securities, and any other property; except that such term does not include stock in the corporation making the distribution (or rights to acquire such stock).
USC Title 26 S 301:
(a) In general
Except as otherwise provided in this chapter, a distribution of property (as defined in section 317(a)) made by a corporation to a shareholder with respect to its stock shall be treated in the manner provided in subsection (c).
This brings up some of the same questions as before. When you receive STEEM, do you now own any more of the website steemit.com than you did before? And if you acquire 51% of the STEEM available, do you get to decide how Dan and Ned run the website? No. So you are not a shareholder, and no stock is being distributed, and since no stock is being distributed, it can not be considered property that is being distributed to shareholders. As there are no shareholders.
USC Title 26 S 1221:
(a) In general
For purposes of this subtitle, the term “capital asset” means property held by the taxpayer (whether or not connected with his trade or business), but does not include—
(3) a copyright, a literary, musical, or artistic composition, a letter or memorandum, or similar property, held by—
(A) a taxpayer whose personal efforts created such property,
(B) in the case of a letter, memorandum, or similar property, a taxpayer for whom such property was prepared or produced, or
(C) a taxpayer in whose hands the basis of such property is determined, for purposes of determining gain from a sale or exchange, in whole or part by reference to the basis of such property in the hands of a taxpayer described in subparagraph (A) or (B);
That is the closest the tax law ever gets to calling a written code "Property" and it says that that kind of property is not included.
USC Title 26 S 61:
(a) General definition
Except as otherwise provided in this subtitle, gross income means all income from whatever source derived, including (but not limited to) the following items:
(3) Gains derived from dealings in property;
That is the closest the tax law every gets to saying that such property should be taxed, but it says "Gains" derived, not the property itself.
So, what are Gains?
The Following case overturned a Law, not just an IRS announcement, where Congress tried to apply taxes to stock dividends, claiming that they were income.
Eisner V Macomber:
https://supreme.justia.com/cases/federal/us/252/189/case.html
"The fundamental relation of "capital" to "income" has been much discussed by economists, the former being likened to the tree or the land, the latter to the fruit or the crop; the former depicted as a reservoir supplied from springs, the latter as the outlet stream, to be measured by its flow during a period of time. For the present purpose, we require only a clear definition of the term "income," as used in common speech, in order to determine its meaning in the amendment, and, having formed also a correct judgment as to the nature of a stock dividend, we shall find it easy to decide the matter at issue. After examining dictionaries in common use (Bouv. L.D.; Standard Dict.; Webster's Internat. Dict.; Century Dict.), we find little to add to the succinct definition adopted in two cases arising under the Corporation Tax Act of 1909 (Stratton's Independence v. Howbert, 231 U. S. 399, 231 U. S. 415; Doyle v. Mitchell Bros. Co., 247 U. S. 179, 247 U. S. 185), "Income may be defined as the gain derived from capital, from labor, or from both combined," provided it be understood to include profit gained through a sale or conversion of capital assets, to which it was applied in the Doyle case, pp. 247 U. S. 183-185. Brief as it is, it indicates the characteristic and distinguishing attribute of income essential for a correct solution of the present controversy. The government, although basing its argument upon the definition as quoted, placed chief emphasis upon the word "gain," which was extended to include a variety of meanings; while the significance of the next three words was either overlooked or misconceived. "Derived from capital;" "the gain derived from capital," etc. Here, we have the essential matter: not a gain accruing to capital; not a growth or increment of value in the investment; but a gain, a profit, something of exchangeable value, proceeding from the property, severed from the capital, however invested or employed, and coming in, being "derived" -- that is, received or drawn by the recipient (the taxpayer) for his separate use, benefit and disposal -- that is income derived from property. Nothing else answers the description. The same fundamental conception is clearly set forth in the Sixteenth Amendment -- "incomes, from whatever source derived"-- the essential thought being expressed with a conciseness and lucidity entirely in harmony with the form and style of the Constitution. "
"It is manifest that the stock dividend in question cannot be reached by the Income Tax Act and could not, even though Congress expressly declared it to be taxable as income, unless it is in fact income."
"Gibbons v. Mahon, 136 U. S. 549, 136 U. S. 559-560. In short, the corporation is no poorer and the stockholder is no richer than they were before."
"And if, for the reasons thus expressed, such a dividend is not to be regarded as "income" or "dividends" within the meaning of the Act of 1913, we are unable to see how it can be brought within the meaning of "incomes" in the Sixteenth Amendment, it being very clear that Congress intended in that act to exert its power to the extent permitted by the amendment."
"Just as we deem the legislative intent manifest to tax the stockholder with respect to such accumulations only if and when, and to the extent that, his interest in them comes to fruition as income, that is, in dividends declared, so we can perceive no constitutional obstacle that stands in the way of carrying out this intent"
"[The 16th Amendment] did not extend the taxing power to new subjects, but merely removed the necessity which otherwise might exist for an apportionment among the states of taxes laid on income. Brushaber v. Union Pacific R. Co., 240 U. S. 1, 240 U. S. 17-19; Stanton v. Baltic Mining Co., 240 U. S. 103, 240 U. S. 112 et seq.; Peck & Co. v. Lowe, 247 U. S. 165, 247 U. S. 172-173. "
"In order, therefore, that the clauses cited from Article I of the Constitution may have proper force and effect, save only as modified by the amendment, and that the latter also may have proper effect, it becomes essential to distinguish between what is and what is not "income," as the term is there used, and to apply the distinction, as cases arise, according to truth and substance, without regard to form. Congress cannot by any definition it may adopt conclude the matter, since it cannot by legislation alter the Constitution, from which alone it derives its power to legislate, and within whose limitations alone that power can be lawfully exercised."
"We are clear that not only does a stock dividend really take nothing from the property of the corporation and add nothing to that of the shareholder, but that the antecedent accumulation of profits evidenced thereby, while indicating that the shareholder is the richer because of an increase of his capital, at the same time shows he has not realized or received any income in the transaction."
"It is equally true that, if he does sell, and in doing so realizes a profit, such profit, like any other, is income, and, so far as it may have arisen since the Sixteenth Amendment, is taxable by Congress without apportionment."
"Thus, the government contends that the tax "is levied on income derived from corporate earnings," when in truth the stockholder has "derived" nothing except paper certificates, which, so far as they have any effect, deny him present participation in such earnings. It contends that the tax may be laid when earnings "are received by the stockholder," whereas he has received none; that the profits are "distributed by means of a stock dividend," although a stock dividend distributes no profits; that, under the Act of 1916, "the tax is on the stockholder's share in corporate earnings," when in truth a stockholder has no such share, and receives none in a stock dividend; that "the profits are segregated from his former capital, and he has a separate certificate representing his invested profits or gains," "
"We cannot disregard the essential truth disclosed, ignore the substantial difference between corporation and stockholder, treat the entire organization as unreal, look upon stockholders as partners when they are not such, treat them as having in equity a right to a partition of the corporate assets when they have none, and indulge the fiction that they have received and realized a share of the profits of the company which in truth they have neither received nor realized."
"Thus, from every point of view, we are brought irresistibly to the conclusion that neither under the Sixteenth Amendment nor otherwise has Congress power to tax without apportionment a true stock dividend made lawfully and in good faith, or the accumulated profits behind it, as income of the stockholder. The Revenue Act of 1916, insofar as it imposes a tax upon the stockholder because of such dividend, contravenes the provisions of Article I, § 2, cl. 3, and Article I, § 9, cl. 4, of the Constitution, and to this extent is invalid notwithstanding the Sixteenth Amendment."
Now, having read all that, you can volunteer to pay the taxes the IRS claims are owed. But you have no obligation to not sue them to get your money back, or any obligation to pay at all and can present the law and Supreme Court Case above to a Federal Judge under Federal Question Jurisdiction.