I think this is the first time that the IRS has explicitly stated that specific identification is a valid accounting method for virtual currency:<p>Q36. I own multiple units of one kind of virtual currency, some of which were acquired at different times and have different basis amounts. If I sell, exchange, or otherwise dispose of some units of that virtual currency, can I choose which units are deemed sold, exchanged, or otherwise disposed of?<p>A36. Yes. You may choose which units of virtual currency are deemed to be sold, exchanged, or otherwise disposed of if you can specifically identify which unit or units of virtual currency are involved in the transaction and substantiate your basis in those units.<p>Q37. How do I identify a specific unit of virtual currency?<p>A37. You may identify a specific unit of virtual currency either by documenting the specific unit’s unique digital identifier such as a private key, public key, and address, or by records showing the transaction information for all units of a specific virtual currency, such as Bitcoin, held in a single account, wallet, or address. This information must show (1) the date and time each unit was acquired, (2) your basis and the fair market value of each unit at the time it was acquired, (3) the date and time each unit was sold, exchanged, or otherwise disposed of, and (4) the fair market value of each unit when sold, exchanged, or disposed of, and the amount of money or the value of property received for each unit.<p>Note, however, that they also clarify that this is not the default accounting method:<p>Q38. How do I account for a sale, exchange, or other disposition of units of virtual currency if I do not specifically identify the units?<p>A38. If you do not identify specific units of virtual currency, the units are deemed to have been sold, exchanged, or otherwise disposed of in chronological order beginning with the earliest unit of the virtual currency you purchased or acquired; that is, on a first in, first out (FIFO) basis.