The U.S. Internal Revenue Service issues Notice 2014-21, ruling that Bitcoin and other virtual currencies are to be treated as property for federal tax purposes, not as currency. This meant capital gains tax applied to every Bitcoin transaction.
The ruling had massive implications: every purchase with Bitcoin became a taxable event. While it legitimized Bitcoin in the eyes of U.S. regulators, it also made using Bitcoin as everyday currency significantly more burdensome.
IRS Virtual Currency Guidance