<prompt> Human: Ive been buying and selling Bitcoin for years. Ive also mined a lot of coins years ago. Im at the a point now where Im selling coins for large sums of cash that I know I cant just ignore on my taxes.Because of the confusing history of my coins, Im not sure how it properly report it. So say I mined 10 coins in 2012, moved them around over the years, sold some, but then bought back in a bunch of times, now sell 7 coins, do I just report the original mined coins as their original somehow? Like, what kind of proof and documentation should I need to get? Hell if I even remember what pools I used to get these lol some of those pools dont even exist anymore :O  <response>: There are a few things you need to get organized.1. You need documentation showing WHEN you obtained the coins CoinbaseExchange transaction history, distribution transaction time stamps from mining.2. You need documentation showing HOW you obtained the coins mined, purchased.Coins obtained from mining income when received. You likely never reported any of this, so you misrepresented your income in prior tax years. Whether intentional or not, under reporting income could lead to tax penalties. Its important to know when you received these mined coins because it would help distinguish between income and capital gains.If you mined bitcoin that had a value of 100 at the time when received I would think it would be treated as such: 100 income when received - taxed at ordinary rates. This becomes your basis in the capital asset. At the time of sale disposal, recognized gainloss Sale price - Basis. Depending on how long you held the capital asset would determine classification of shortlong-term gain treatment.For the coins you purchased from an exchange, whatever you paid becomes your basis no different than a stock.Im a CPA, but not a tax expert. This is more of an organizational problem for you than a problem for your would be accountant, IMO. Please get organized and consult with a local CPA to review your situation.Edit: For 2017 Ill be dealing with this as well since I sold this year too. My situation doesnt seem as messy as yours though. I never mined, and all my buying history is from Coinbase. They have records, and I have my own. 