Each exchange of one cryptocurrency for another cryptocurrency is technically a "sale", (as would an exchange of a cryptocurrency for US dollars), that does need to be reported.
The IRS has made that clear in Notice 2014-21
Q-6: Does a taxpayer have gain or loss upon an exchange of virtual currency for other property?
A-6: Yes. If the fair market value of property received in exchange for virtual currency exceeds the taxpayer’s adjusted basis of the virtual currency, the taxpayer has taxable gain. The taxpayer has a loss if the fair market value of the property received is less than the adjusted basis of the virtual currency. See Publication 544, Sales and Other Dispositions of Assets , for information about the tax treatment of sales and exchanges, such as whether a loss is deductible.
Q-7: What type of gain or loss does a taxpayer realize on the sale or exchange of virtual currency?
A-7: The character of the gain or loss generally depends on whether the virtual currency is a capital asset in the hands of the taxpayer. A taxpayer generally realizes capital gain or loss on the sale or exchange of virtual currency that is a capital asset in the hands of the taxpayer. For example, stocks, bonds, and other investment property are generally capital assets. A taxpayer generally realizes ordinary gain or loss on the sale or exchange of virtual currency that is not a capital asset in the hands of the taxpayer. Inventory and other property held mainly for sale to customers in a trade or business are examples of property that is not a capital asset. See Publication 544 for more information about capital assets and the character of gain or loss
Tom Young
