from turbo tax USA laws
"When you mine the coins, you have income on the day the coin is "created" in your account at that day's exchange value."
You're not really wrong, but:
A) whether or not they are correct, NEVER RELY ON TURBO TAX FOR INFORMATION. If you earn more than $50K/year, they are a bad choice, and if your supplemental income from mining is substantial, get an accountant.
B) there is absolutely no way that the IRS is asking for value at time of realization, because it would bankrupt them to calculate that rate for a handful of miners, much less all. Market fluctuations are constant, and you mine in increments every second. No way they can determine that, and no way they can audit every single miner to determine fraud. Again, talk to an actual accountant about what you may or may not owe.