tl;dr(I don't want to click the article)
Trades between coins is taxable if profit is made, not just when it is cashed to fiat.
Coinbase/Gdax (and I would assume other "buy with fiat" platforms) are required to report if more than $20,000 USD is made in profit.
Long-term gains and short-term gains will be taxed differently. Short term gains, (anything held for less than a year) may be taxed as much as 39.6% by the federal government, and up to 13% by the state.
More than $10,000 in a wallet or market based outside of the United States, may now need to be reported to the IRS, as it counts as Foreign Holdings/Assets.
Forbes has stated, owning a Cryptocurrency during a fork, and being "gifted" the new coin also counts as taxable income.
If the market bubble bursts and losses are abundant, the IRS will still expect payment for any forks, trades, or financial gains of any kind.
Some charities are now directly accepting crypto as a payment method. You can receive tax deductions and avoid paying capital gains tax on the amount donated.
I have been recommended using [cointracking.info] for my taxes and I am pretty much decided on it at this point. I would recommend looking at what they have to offer. This would be especially useful if you have high numbers of trades on different markets and platforms. This service appears to be free for people who made less than 200 trades over the last year.
My personal thoughts.
Don't get me wrong, I'm not going to stop trading and holding crypto. But, I do have to admit that a possible 50%+ tax definitely going to change the way I think about profits. People already pay fees for every buy/sell/trade they make and This is going to make everything a lot harder for everyone besides Big Brother.
Either way, I hope this information was useful. I tried to make my first post about something I have personally been thinking about a lot lately. Link for Info below
https://qz.com/1156706/a-guide-to-paying-taxes-on-bitcoin-investments/