Consider your growing stash of bitcoins. If you're the type who mines for bitcoins, the market value of what you receive counts as part of your gross income... just in time for tax season, naturally. Conducting commerce with Bitcoin may have become much trickier on the small scale, too. You have to deal with capital gains and losses for Bitcoin transactions if the value of those bitcoins fluctuates (doesn't it always?). Bloomberg
explains what this means well:
Under the ruling, purchasing a $2 cup of coffee with bitcoins bought for $1 would trigger $1 in capital gains for the coffee drinker and $2 of income for the coffee shop.
Reporting those gains and losses may not be too troublesome for big, infrequent exchanges, but businesses that deal with plenty of smaller ones could have plenty of record keeping to do. And if you're a business that (for some reason) pays employees with bitcoins, that virtual wage is subject to income tax withholding. If those employees didn't get W-2s before, voilà -- they need 'em now. Long story short, bitcoin owners: Start keeping track of everything lest the taxman take issue with your methods and come poking around.