FULL DISCLOSURE: I AM NOT A TAX PROFESSIONAL AND YOU SHOULD CONSULT A TAX PROFESSIONAL IF YOUR GAINS FROM BITCOIN EXCEED INCIDENTAL (less than $300 per year) VALUE

As I understand it, Bitcoin is an INVESTMENT property subject to the same capital gains/loss reporting as stocks, bonds, and like entities.

You are responsible for maintaining a record of the value of the investment at the time of receipt. This means if you are paid in Bitcoin (or any cryptocurrency) at 06/21/2017::04:00:00 (the exact time of this post), you should record the value in USD of that coin at that moment. Because this is not always practical (and the US has no evidence of the exact time you received a transaction) you can use a reasonable daily average price from a "recognized source" (I'd go with Google). This receipt of coin is considered a taxable capital gain, but you may not have to pay tax on it until it is liquidated (this is deferred taxation).

You are also responsible for documenting any like-kind exchange (value for value) when you trade one coin for another. This is neither a gain nor a loss.

Finally you must report any sale of coin into FIAT or a FIAT like (gift cards, unlike property, labor) at the rate you received for it less any transaction costs. The difference between this number and the value at receipt is your capital gain/loss from the transaction and you must pay tax or receive a refund for this gain/loss.

Hopefully that clears things up a bit