In 2014 when Gox went down, it took a lot of people's BTC with it. I am not looking for a discussion on what/why happened. I have been hodl BTC all this time, and at the end of 2017 I sold a little on Coinbase.
It's much below the level of USD$20k that is being bantered about, on Coinbase reporting to the IRS. If I sell in the future, I don't want the IRS to flag me as anything, and look back to say "Ah, in 2017 you sold a few fractions of BTC and did not report it", so I plan to enter it as long-term capital gains for 2017 (I've held it for more than a year and a day).