 Attributes of a real currency, as defined in 2011 in the Code of Federal Regulations, such as real paper money and real coins are simply that they act as legal tender and circulate "customarily".The IRS decided in March 2014, to treat bitcoin and other virtual currencies as property for tax purposes, not as currency.Some have suggested that this makes bitcoins not fungible—that is one bitcoin is not identical to another bitcoin, unlike one gallon of crude oil being identical to another gallon of crude oil—making bitcoin unworkable as a currency.