yeah but what if you end up funneling money from bitcoin gains back into your bank? wouldn't the IRS know about it? btw isn't capital gains tax cheaper than income?
In most cases, yes: capital gains tax is preferable. The capital gains tax rate on long-term gains for 2011 returns in the US was 15%; this is being increased to 20% in tax years after 2012 (however, it will be 0% for taxpayers in the 10-15% tax brackets). Short-term capital gains are generally taxed at the ordinary tax rate of the taxpayer.
The IRS doesn't monitor the bank accounts of taxpayers, so they wouldn't know whether or not the taxpayer is funneling money back and forth. However, the IRS will require documentation of trading activities in the event of an audit. In that situation, the IRS can request bank statements for income verification (I have two clients now who are in a similar situation).
Generally speaking and in theory, you can claim whatever the hell you want on your taxes: you just need to be able to back it up when the IRS starts poking at it. And the more "extreme" (or for a more accurate term, questionable) your claims are, the more likely the IRS is going to grab the pokin' stick.
And it's important to remember this too: when the IRS audits a return, they audit the
full return. So if the IRS looks at one thing on a return and they feel it's a questionable claim, they could audit the return and find out about something else entirely.
For example: a delivery driver has $2,000 in cash tips that he doesn't claim on his return, but he does claim mortgage interest reported on a 1098 in the amount of $10,000. The IRS reviews the return and they think the mortgage interest claimed is more than it should be. They audit the full return and notice the $2,000 worth of deposits to discover that the taxpayer didn't claim those tips. The taxpayer will end up owing more taxes, and possibly a tax penalty.
With cash and coins (both US and Bit), it's up to the individual on whether or not to report them. The IRS may not notice them since it's hard to prove, but they may find out about them if they noticed something else.
The difficulty with Bitcoin is knowing what it should be classified as. As I said before, there are no definitive tax laws regarding them at this point. If someone wants to play it safe, I would recommend they report Bitcoins received as payment for goods or services converted to USD as other income on line 21, and profit/loss from Bitcoin trading as capital gains and losses.