Some problems that I think are awfully difficult to solve:
1. If you played SatoshiDice you need report that on your tax return. Each winning and losing SatoshiDice bet creates a taxable event.
2. If you had bitcoin transactions in prior years, 2012 and earlier, you need to file an amended return and either pay additional tax or get a refund.
4. If you lost bitcoins you need to report that. (Scammed, stolen, pirate@40, coffee on the computer)
5. You need records or every bitcoin transaction.
6. You need records of the fair market value of bitcoins (for much of bitcoin's history there has not been a fair market, MtGox!)
7. If you get auditied then your records have to satisfy the auditor otherwise they will make the worst possible assumptions about your transactions, i.e. without a proper receipt your cost basis is $0 maximizing the capital gains tax.
The safe route I would recommend for now when sending or receiving taxable Bitcoins is to record the dollar value of the Bitcoins at the time they are sent or received for tax reporting. This will probably be a pain given how much the price can fluctuate, but it is the safest route.
1. Correct. As I said: record the dollar amount of each SD gain as you win the coins and the dollar amount of the coins you spent. You would claim the winnings as line 21 income and deduct the losses (to the extent of winnings) on a schedule A if you itemize your deductions. Maybe Satoshi Dice will implement tax forms into their site at some point, which I imagine they could only do if you registered an account with them or something.
2. You may not have to amend your previous year returns since the IRS did not regulate Bitcoin earnings in those years. The IRS also doesn't have a record of BTC you earned in previous years, so I wouldn't worry about an audit. Keep in mind that the IRS generally allows amended returns for the past three tax years only.
4. You could claim such losses on form 4684, but I imagine you would have to make a very strong case to prove you had ownership of such lost or stolen coins for the IRS to allow such a deduction. And, again, you would probably have to claim the loss on the value of the coins at the time of the theft, fraud, or loss.
5. Yes, I would highly recommend (like I said earlier) recording all Bitcoin dollar values in and out for tax purposes. A simple Excel spreadsheet would probably suffice for this.
6. Yup, same as #5. I don't think the FMV of Bitcoin varies enough from wallet-to-wallet, exchange-to-exchange, for it to matter too much which source you use. For example, I use the send value of my blockchain app to record the value of my Bitcoins.
7. The biggest target area for IRS audits will be, I imagine, schedule D Bitcoin transactions (which tend to be a target form on its own). Hopefully the IRS will release more guidelines for Bitcoin related tax reporting, but for the time being just do the best you can to record what you get when you get it. If you can show the IRS that you used reasonable methods at your disposal to record what you pay and earn, you should be fine. I also imagine it'll be difficult for the IRS, in the beginning, to harshly enforce Bitcoin transactions, given the newness of the ruling and the nature of the currency (or property, as per the IRS) itself.