True, the IRS can't expect us to follow tax rules regarding bitcoin that haven't even been made yet....
You will probably be fine if you are making a reasonable attempt to calculate and pay taxes. It would only matter if you get audited, and in that case it is hard to imagine that you could be penalised for not following rules that didn't exist. At the very worst you would have to retroactively pay extra from previous years.
Most accountants I've seen are suggesting filing as general assets, because it is the general catch all for something that isn't anything else. So you would pay taxes on any capital gains. However, some are going to file as currency, so they can be conservative in taxes owed to ensure you aren't underpaying.
For capital gains, you would still need to calculate the cost basis for each coin when you sell, and I created a website where you can upload all your trade data and we work it all out.
https://bitcointaxes.infoWe combine all your trades and work them out in a FIFO list, split and combining as necessary. It shows your long-term and short-term capital gains as well as all your Sales of Assets that can then be included in your IRS Form 8949.
You can also use specific identification to be able to change the order of your trades, which could be beneficial to make them long-term and reduce your tax liability.
It also does alt-coins and cross-coin trading. Cross-coin trading is done assuming they are NOT like-for-like and so calculates the fair value of a coin, e.g. if you bought 100 LTC for 1 BTC, it considers it a Sell of 1 BTC into USD with the daily average price, then buying 100 LTC with that USD. This was the gains on BTC and the cost basis on the LTC can all be calculated.
Check if out. It's free for BTC only trades and there is a Premium version for alt-coins and previous year.